Some observations on the life history of Podocarpus falcatus

1960 ◽  
Vol 8 (3) ◽  
pp. 243 ◽  
Author(s):  
TGB Osborn
Keyword(s):  
Life History ◽  
Life Cycle ◽  
Pollen Tube ◽  
Mother Cell ◽  
Nuclear Division ◽  
Embryonic Cells ◽  
Linear Tetrad ◽  
Zygote Nucleus ◽  
Layer Membrane ◽  
History Of

Podocarpus falcatus (R.Br. ex Mirb.) belongs to the 1-year life cycle type of podocarp. Ripe seeds are shed 12–13 months after pollination. There is a single gynospore mother cell in a well-defined tapetum, and the inner spore of a linear tetrad is functional. Pollen tubes make contact with the developing female prothallus before the stage of free nuclear division is complete. They continue to grow downwards between it and the nucellus. There are several superficial archegonia, some of which may be enveloped by a common jacket layer. They are of intermediate length, and develop along the line of contact between the pollen tube and prothallus. The gynospore layer membrane remains thin at this point. Five free mitoses of the zygote nucleus take place, the first two in the mid archegonial area. The proembryonic nuclei become tiered with a low number in the embryonic layer. The embryonic cells have the usual binucleate phase followed by tetrad formation. Simple polyembryony is common, and though fission may occur it is not general.

scholarly journals CHROMOSOMAL ALTERNATION OF GENERATIONS IN NEREOCYSTIS LUETKEANA (MERTENS) POSTELS AND RUPRECHT

1961 ◽  
Vol 39 (7) ◽  
pp. 1711-1724 ◽  
Author(s):  
Lindley Kemp ◽  
Kathleen Cole
Keyword(s):  
Life History ◽  
Life Cycle ◽  
Nuclear Division ◽  
Basal Cells ◽  
Cytological Examination ◽  
Male And Female ◽  
Nereocystis Luetkeana ◽  
History Of ◽  
Alternation Of Generations

A cytological examination of the life history of Nereocystis luetkeana has shown that an alternating chromosome number corresponds to the morphological alternation of generations. The first division sequence of the zoosporangial nucleus is meiotic and is followed by three, usually synchronous, mitotic divisions. Thirty-two zoospores are liberated from each sporangium, and their germination gives rise to male and female gametophytes. Genotypic determination of the sexes is believed to take place in Nereocystis. Mitosis in the gametophytes is regular and cytokinesis follows each nuclear division, producing few cells in the female and many cells in the male gametophytes. Thirty-one chromosomes can be counted at the mitotic prophase. Oogamy exists in Nereocystis and fertilization takes place after the egg is extruded from the oogonium. Nuclear division in the sporophyte appears to be preceded by division of the nucleolus. Colorless and non-septate rhizoids develop as elongations of the basal cells of the sporophyte.Temperature is an important factor in the development of various stages of the life cycle of Nereocystis grown in culture, particularly in the gametophytic stage where sexual structures are produced only at temperatures less than 10 °C and vegetative growth is most prolific at 14–18 °C.Some of the unfertilized eggs develop parthenogenetically and give rise to stunted, deformed plants with multinucleate cells.

scholarly journals The life-cycle of the nodule organism, bacillus radicicola ( Beij. ), in soil and its relation to the infection of the host plant

1926 ◽  
Vol 99 (699) ◽  
pp. 427-451 ◽  
Keyword(s):  
Life History ◽  
Life Cycle ◽  
Host Plant ◽  
Internal Structure ◽  
Mother Cell ◽  
Leguminous Plant ◽  
Young Culture ◽  
History Of ◽  
The Subject ◽  
Straight Rod

The existence of changes in the form of Bacillus radicicola has been known since Beijerinck (2) first isolated it in 1888 from leguminous plant nodules. He observed the motile “swarmer” stage as well as the branching forms, whose nature was already the subject of controversy. About the same time the development of straight-rod forms of the organism was described by Prazmowski (14). Numerous writers have since observed the existence of the organism in the three conditions of straight rods, branching rods and cocci (for references, see Löhnis, 1921 (10)). In 1916 Löhnis and Smith (11) claimed that the various forms constituted a definite life-cycle through which the organism normally passes, and this cycle, as seen in cultures, was carefully described in 1919 by Bewley and Hutchinson (3). In a vigorous young culture, the predominating form of the organism is a short, evenly staining rod (fig. 1). These rods soon undergo a change in internal structure, the staining material becoming segregated into bands crossing the cell. During this banded stage the cells frequently become swollen, distorted, and branched, the so-called “bacteroids” (Brunchorst (4)), but this irregularity of form is not an essential part of the life-cycle, but would appear to be a response to conditions of the environment (Buchanan, 1909) (5). The banded cells give rise to the cocci by further condensation of the bands. The origin of the cocci within the mother-cell was described and illustrated in 1891 by Morck (12), who was the first to appreciate the relation of the internal structure of the cell to the life-history of the organism. The cocci are usually released in a non-motile condition, and afterwards develop flagella, becoming actively motile, the “swarmers” of Beijerinck (2). Under certain conditions, however, the cocci develop flagella while still enclosed within the mother-cell. This condition has been described by Greig-Smith (8) and the observation confirmed by one of the present authors (7). The cocci eventually become elongated and thus pass into the unbanded rod stage. The flagella, which are developed on the cocci, persist after this elongation, but are soon lost: the rods then become non-motile. The development of motility in a culture is thus intimately associated with the appearance of the coccus stage.

The reproduction and larval development of Nereis fucata (Savigny)

1959 ◽  
Vol 38 (1) ◽  
pp. 65-80 ◽  
Author(s):  
J. B. Brown-Gilpin
Keyword(s):  
Life History ◽  
Life Cycle ◽  
Experimental Methods ◽  
Point Of View ◽  
Hermit Crabs ◽  
Special Importance ◽  
Reproductive Patterns ◽  
Complete Life Cycle ◽  
History Of ◽  
The Many

The wide variety of reproductive patterns and behaviour in the many species of Nereidae already studied clearly justifies further research. But the life history of Nereis fucata (Savigny) is not only of interest from the comparative point of view. Its commensal habit (it occurs within shells occupied by hermit crabs) immediately gives it a special importance. This alone warrants a detailed study, particularly as no commensal polychaete has yet been reared through to metamorphosis and settlement on its host (Davenport, 1955; Davenport & Hickok, 1957). The numerous interesting problems which arise, and the experimental methods needed to study them, are, however, beyond the range of a paper on nereid development. It is therefore proposed to confine the present account to the reproduction and development up to the time when the larvae settle on the bottom. The complete life cycle, the mechanism of host-adoption, and related topics, will be reported in later papers.

scholarly journals A STUDY OF THE LIFE HISTORY OF TRICHOBILHARZIA CAMERONI SP. NOV. (FAMILY SCHISTOSOMATIDAE)

1953 ◽  
Vol 31 (4) ◽  
pp. 351-373 ◽  
Author(s):  
Liang-Yu Wu
Keyword(s):  
Life History ◽  
Life Cycle ◽  
Room Temperature ◽  
Migratory Birds ◽  
Local Infection ◽  
Domestic Ducks ◽  
Ottawa River ◽  
Daughter Sporocyst ◽  
Physa Gyrina ◽  
History Of

A cause of swimmer's itch in the lower Ottawa River is Trichobilharzia cameroni sp. nov. Its life cycle has been completed experimentally in laboratory-bred snails and in canaries and ducks, and the various stages are described. The eggs are spindle-shaped. The sporocysts are colorless and tubular. Mother sporocysts become mature in about a week. The younger daughter sporocyst is provided with spines on the anterior end and becomes mature in about three weeks. The development in the snail requires from 28 to 35 days. A few cercariae were found to live for up to 14 days at 50 °C., although their life at 16° to 18 °C. was about four days. Cercariae kept at room temperature for 60 to 72 hr. were found infective. The adults become mature in canaries and pass eggs in about 12 to 14 days. Physa gyrina is the species of snail naturally infected. It was found in one case giving off cercariae for five months after being kept in the laboratory. Domestic ducks were found to become infected until they were at least four months old, with the parasites developing to maturity in due course; no experiments were made with older ducks. Furthermore, miracidia were still recovered from the faeces four months after the duck had been experimentally infected, and it is suggested that migratory birds are the source of the local infection.

The life history of Pleurogenoides malampuzhensis sp. nov. (Digenea: Pleurogenidae) from amphibious and aquatic hosts in Kerala, India

2013 ◽  
Vol 88 (2) ◽  
pp. 230-236 ◽  
Author(s):  
R. Brinesh ◽  
K.P. Janardanan
Keyword(s):  
Life History ◽  
Life Cycle ◽  
Related Species ◽  
Growth And Development ◽  
Systematic Position ◽  
Patent Period ◽  
Hoplobatrachus Tigerinus ◽  
Life Cycle Stages ◽  
Muscle Tissues ◽  
History Of

AbstractThe life-cycle stages of Pleurogenoides malampuzhensis sp. nov. infecting the Indian bullfrog Hoplobatrachus tigerinus (Daudin) and the skipper frog Euphlyctiscyanophlyctis (Schneider) occurring in irrigation canals and paddy fields in Malampuzha, which forms part of the district of Palakkad, Kerala, are described. The species is described, its systematic position discussed and compared with the related species, P. gastroporus (Luhe, 1901) and P. orientalis (Srivastava, 1934). The life-cycle stages, from cercaria to egg-producing adult, were successfully established in the laboratory. Virgulate xiphidiocercariae emerged from the snail Digoniostoma pulchella (Benson). Metacercariae are found in muscle tissues of dragonfly nymphs and become infective to the frogs within 22 days. The pre-patent period is 20 days. Growth and development of both metacercariae and adults are described.

Analysis of a Population Sampling Method for the Lodgepole Needle Miner in Canadian Rocky Mountain Parks

1952 ◽  
Vol 84 (10) ◽  
pp. 316-321 ◽  
Author(s):  
R. W. Stark
Keyword(s):  
Life History ◽  
Life Cycle ◽  
Sampling Method ◽  
Rocky Mountain ◽  
Fixed Time ◽  
Forest Stand ◽  
Population Sampling ◽  
Adequate Sampling ◽  
History Of ◽  
External Feeding

General.—The purpose of this paper is to analyse a sampling method devised to assess larval populations in an outbreak of the lodgepole needle miner, Recurvaria milleri Busck (Busck 1914, Hopping 1945).The problem of developing an adequate sampling method is intimately concerned with the life-history of the insect, the region of the outbreak and the nature of the forest stand in which the outbreak occurs. In sampling most defoliator populations the problem is made more difficult by external feeding and wandering habits, hence it is usually done in some relatively inactive stage at a fixed time. de Gryse (1934) describes the problems inherent in sampling these insects. The needle miner, however, is fixed in its location for most of its life-cycle and is therefore readily obtainable for study. The problem here is reduced to a statistical one, that of obtaining an acceptable sample i.e. within suitable error limits with due regard for existing variables.

scholarly journals LIFE HISTORY, NON-SPECIFICITY, AND REVISION OF THE GENUS CHORIOPTES, A PARASITIC MITE OF HERBIVORES

1957 ◽  
Vol 35 (6) ◽  
pp. 641-689 ◽  
Author(s):  
Gordon K. Sweatman
Keyword(s):  
Life History ◽  
Life Cycle ◽  
Additional Species ◽  
Sheep And Goats ◽  
History Of ◽  
Parasitic Mite

Chorioptic mange mites have been reared in vitro on epidermal debris. The life history of the mite has been observed, and each stage in the cycle described. Mites from the cow, horse, goat, sheep, and llama have been shown to be identical biologically and morphologically, and the specific names of equi, caprae, and ovis have been synonymized with C. bovis. The in vitro life cycle has been completed on epidermal debris from a variety of wild Cervidae, Bovidae, and Equidae, as well as on material from several breeds of domestic cattle, horses, sheep, and goats. From these and other data, three additional species or subspecies of Chorioptes were synonymized also with C. bovis. Only one other species, namely C. texanus, remains in the genus.

The life history of Scaphiostomum pancreaticum McIntosh, 1934 (Trematoda: Brachylaemidae)

1972 ◽  
Vol 50 (2) ◽  
pp. 201-204 ◽  
Author(s):  
Doris N. Jensen
Keyword(s):  
Life History ◽  
Life Cycle ◽  
Gastric Juice ◽  
Tamias Striatus ◽  
History Of ◽  
Anguispira Alternata ◽  
Cercarial Emergence

The life cycle of the brachylaemid trematode Scaphiostomum pancreaticum McIntosh, 1934, was completed experimentally in the laboratory. Eggs were obtained from trematodes removed from naturally infected Tamias striatus. Eggs are mature when laid and hatch naturally only after ingestion by a snail. In vitro hatching and subsequent examination of the miracidium was accomplished in snail gastric juice. Sporocysts developed in Anguispira alternata and cercarial emergence began 129 days after infection. Metacercariae developed in the kidney of A. alternata, Triodopsis albolabris, and Haplotrema concavum and were infective to the chipmunk after 5 months, and ovigerous adults were obtained in 30 days. This is the first description of the life cycle of a member of this genus.

THE ECOLOGY AND LIFE HISTORY OF RETUSA OBTUSA (MONTAGU) (GASTROPODA, OPISTHOBRANCHIA)

1967 ◽  
Vol 45 (4) ◽  
pp. 397-405 ◽  
Author(s):  
S. Tyrell Smith
Keyword(s):  
Life History ◽  
Life Cycle ◽  
Life Span ◽  
High Tide ◽  
Breeding Period ◽  
Protandrous Hermaphrodite ◽  
History Of ◽  
Natural Breeding ◽  
One Year ◽  
Short Time

The habitat, diet, life history, and reproductive cycle of Retusa obtusa were investigated over a period of [Formula: see text] years in a population found in the Inner Harbour at Barry, Glamorgan, U.K. A technique was devised for extracting Retusa from the mud of this area. R. obtusa occurs in the topmost 3.5 cm of fine mud covering Barry harbor, which is immersed by the sea for only a short time at each high tide. The principal prey was found to be Hydrobia ulvae.The life cycle was found to be annual, the adults dying in spring, following the natural breeding season. Occasionally, a short extra breeding period occurs in the fall. The life span in no case greatly exceeded one year. Retusa is a protandrous hermaphrodite, and copulates in the fall. The eggs mature through the late fall and the winter, a few at a time, until oviposition occurs in the spring. The average number of eggs produced per individual was 33, deposited in 1–4 egg batches. Development is direct.

BIONOMICS OF BLATTISOCIUS KEEGANI (FOX) (ACARINA: ASCIDAE), A PREDATOR ON EGGS OF PESTS OF STORED GRAINS

1967 ◽  
Vol 45 (6) ◽  
pp. 1093-1099 ◽  
Author(s):  
Philip S. Barker
Keyword(s):  
Life History ◽  
Life Cycle ◽  
Female Offspring ◽  
Finite Rate ◽  
Rate Of Increase ◽  
Stored Grains ◽  
History Of ◽  
Cryptolestes Turcicus

The life history of Blattisocius keegani (Fox) was studied at 60, 72, and 80 °F, and at relative humidities (r.h.) of 70 to 75% and 95 to 100%. A life cycle of 6 to 7 days was found at 80 °F. Oviposition was studied at 80 °F and 70 to 75% r.h.; the finite rate of increase (λ) was 3.33 female offspring per female per week. Approximately three Cryptolestes turcicus (Grouvelle) eggs were required to rear one B. keegani to adulthood at 80 °F and 70 to 75% r.h. Female B. keegani that consumed one C. turcicus egg per day were able to oviposit. The hosts investigated included eggs of six species of beetles, and two species of mites that infest stored grains.

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