scholarly journals On the cytology of apogamy and apospory.—1. Preliminary note on apogamy

1903 ◽  
Vol 71 (467-476) ◽  
pp. 453-457 ◽  
Keyword(s):  
Life History ◽  
Life Histories ◽  
The Other ◽  
Preliminary Note ◽  
History Of

The phenomena of apogamy and apospory have always been regarded as “short cuts” in the life history of ferns, and the fact that apparently either generation may be directly produced from the other, without the intervention of oosphere or spore respectively, has been taken to indicate that the gametophyte and sporophyte are homologous phases in the life histories of these plants.

scholarly journals The chromosome cycle in Coccidia and Gregarines

1915 ◽  
Vol 89 (610) ◽  
pp. 83-94 ◽  
Keyword(s):  
Life History ◽  
Life Cycle ◽  
Chromosome Numbers ◽  
Life Histories ◽  
The Other ◽  
Chromosome Cycle ◽  
History Of ◽  
Careful Investigation

Despite the large amount of work which has already been devoted to the study of the Coccidia and Gregarines, very little indeed is known definitely about the behaviour of the chromosomes in these Protozoa. Not only has the chromosome cycle been left uninvestigated and undescribed in the majority of these organisms which have hitherto been studied, but the very existence of chromosomes in the nuclear divisions at many stages in the life-history of certain forms has even been denied; and the most contradictory and unsatis­factory accounts have been given of that most important phase in the life-cycle of the chromosomes—the phase of meiosis, or reduction. In order to fill up this gap in our knowledge of the Sporozoa, we have made —during the last few years—a very detailed study of the chromosomes of a coccidian and a gregarine. One of us (C. D.) has investigated the coccidian Aggregate eberthi Labbé, whilst the other (A. P. J.) has studied the gregarine Diplocystis schneideri Kunstler. Careful investigation of these two organisms has shown that the nuclear divisions at all stages in the life-histories are mitotic, and that the chromosome numbers are remarkably constant.

POST EMBRYOLOGICAL DEVELOPMENT OF EPHEMEROPTERA (MAYFLIES). EXTERNAL CHARACTERS ONLY

1935 ◽  
Vol 12 (4) ◽  
pp. 433-478 ◽  
Author(s):  
F. P. Ide
Keyword(s):  
Life History ◽  
Structural Change ◽  
Life Histories ◽  
External Genitalia ◽  
The Other ◽  
Embryological Development ◽  
First Instar ◽  
Definite Case ◽  
History Of ◽  
Number Of Segments

The development of external structures is followed from hatching to maturity. The life histories of two species Stenonema canadense Wlk. and Ephemera simulans Wlk. are described in detail and less complete accounts given of nine others.Each moult results in a change in the number of segments in the caudal filaments and on this basis it has been possible to determine the number of instars. In Stenonema canadense the number was found to be between 40 and 45, and in Ephemera simulans about 30. Segments are added to the caudal filaments of the former at each moult in the following way: one in each of the first two moults, two in each of the next three, three in the next and four at each subsequent nymphal moult. In the change from nymph to subimago distal segments are dropped in Ephemera and probably in Stenonema also.Mouth parts are very different in the newly hatched than in the full grown nymph as described for Stenonema canadense.A definite case of a hypermetamorphosis of the tarsus and its claws appears in the life history of Epeorus humeralis and Iron pleuralis.Gills are absent in the first instar in all the species studied. In some species they appear simultaneously on all the gill bearing segments at the first moult. In others they appear on segments five and six only at this moult, those of the other segments appearing only after several moults. The internal or secondary ramus of the gills appears much later in the nymphal life. The ultimate shape of the gill is influenced in some cases by the fact that the gills of segments five and six are segmented or unsegmented.In S. canadense the wing pads make their appearance in about the fifteenth from the last instar and the claspers and external genitalia of the male are apparent in about the eighth from the last instar.At each moult there is some structural change in the nymph adapting it to the environment. The environmental relation is being constantly changed by increase in size of the organism, thus necessitating these adaptations to preserve an equilibrium.

scholarly journals Enumerative studies on Trypanosoma gambiense and Trypanosoma rhodesiense in rats, guinea-pigs, and rabbits; periodic variations disclosed. (Preliminary note.)

1911 ◽  
Vol 83 (563) ◽  
pp. 206-211 ◽  
Keyword(s):  
Life History ◽  
Guinea Pigs ◽  
Peripheral Circulation ◽  
Tropical Medicine ◽  
The Other ◽  
Tropical Diseases ◽  
Research Committee ◽  
Preliminary Note ◽  
History Of ◽  
Trypanosoma Gambiense

The investigations were undertaken at the suggestion of Major R. Ross, under funds allotted by the Tropical Diseases Research Committee in the case of one of us (H. B. F.) and under the Sir Edwin Durning-Lawrence Fund in the case of the other (J. G. T.). The researches were necessary in order to determine whether a regular periodic increase in the trypanosomes in the peripheral circulation of subinoculated animals occurred, like that found by R. Ross and D. Thomson (1910) in a case of Rhodesian Sleeping Sickness, and whether this numerical cyclical development had a definite significance in the life-history of the parasite, which it would be necessary to consider in the case of treatment by drugs or other methods. Our work was done in the Liverpool School of Tropical Medicine.

A comparative study of the life histories of Nematodirus battus and N. filicollis, nematode parasites of sheep

Parasitology ◽  
1959 ◽  
Vol 49 (3-4) ◽  
pp. 374-386 ◽  
Author(s):  
R. J. Thomas
Keyword(s):  
Life History ◽  
Intestinal Mucosa ◽  
Related Species ◽  
Life Histories ◽  
Basic Pattern ◽  
Culture Methods ◽  
Closely Related Species ◽  
Nematode Parasites ◽  
History Of ◽  
Comparative Description

1. The life history of N. battus is described, and a comparative description of the life history of N. filicollis is given.2. The life histories of these two species are compared with those of N. spathiger and N. helvetianus, two closely related species, and are shown to follow the same basic pattern, with minor variations in timing which appear to be specific in nature, and not related to differences in culture methods or host species.3. The pathogenesis of Nematodirus species is discussed and related to the migration of larvae into the intestinal mucosa during development.

III.—The Life-history and Cytology of Didymium nigripes Fr.

1932 ◽  
Vol 57 (1) ◽  
pp. 93-142 ◽  
Author(s):  
Elsie J. Cadman
Keyword(s):  
Life History ◽  
Life Histories ◽  
Important Research ◽  
Great Work ◽  
Animal Kingdom ◽  
History Of ◽  
Natural Groups

Since 1860, in which year De Bary published his great work Die Mycetozoen, the investigation of the life-history of members of the Mycetozoa has aroused a considerable amount of interest, and a great deal of important research has been carried out in this connection. The group of organisms is particularly interesting, because it lies on the borderline between plant and animal kingdoms, and it is very possible that a detailed investigation of several species of the Mycetozoa might be of considerable assistance in elucidating certain obscure points in the life-histories of higher members of both the great natural groups. The term “Mycetozoa,” which we owe to De Bary, will be used throughout in preference to the older term “Myxogastres” invented by Fries (32, p. 2), and that of “Myxomycetes” first employed by Link (32, p. 2). “Mycetozoon,” or “fungus-like animal,” is a very appropriate description of a member of the group, since during part of its life-history it exhibits distinctly animal-like characters, and the individuals move rapidly by means of flagella, whilst later, during the development of the sporangium, a plant-like form is assumed. The combination of plant and animal characters has given rise to much discussion as to the position of the Mycetozoa in plant or animal kingdom, and the group has been claimed by both zoologists and botanists.

scholarly journals The application of life history information to the conservation management of Chrysoritis butterflies (Lepidoptera: Lycaenidae) in South Africa

Koedoe ◽  
2004 ◽  
Vol 47 (1) ◽  
Author(s):  
R.F. Terblanche ◽  
H. Van Hamburg
Keyword(s):  
South Africa ◽  
Life History ◽  
Life Histories ◽  
Host Plants ◽  
Conservation Management ◽  
Aesthetic Value ◽  
Wing Patterns ◽  
In The Wild ◽  
History Of ◽  
Voucher Specimens

Due to their intricate life histories and the unique wing patterns and colouring the butterflies of the genus Chrysoritis are of significant conservation and aesthetic value. Thisoverview probes into practical examples of butterfly life history research applicable to environmental management of this relatively well-known invertebrate group in South Africa. Despite the pioneer work on life histories of Chrysoritis in the past, more should be done to understand the life history of the butterflies in the wild, especially their natural host plants and the behaviour of adults and larvae. A system of voucher specimens of host plants should be introduced in South Africa. Although various host plant species in nature are used by the members of Chrysoritis, including the Chrysoritis chrysaor group, the choice of these in nature by each species is significant for conservation management and in the case of Chrysoritis aureus perhaps even as a specific characteristic.A revision of the ant genus Crematogaster will benefit the conservation management of Chrysoritis species since some of these ant species may consist of a number of specieswith much more restricted distributions than previously thought. Rigorous quantified tudies of population dynamics of Chrysoritis butterflies are absent and the introductionof such studies will benefit conservation management of these localised butterflies extensively.

Syphilitic General Paralysis

1893 ◽  
Vol 39 (165) ◽  
pp. 217-224
Author(s):  
M. J. Nolan
Keyword(s):  
Life Histories ◽  
The Other ◽  
Fin De Siecle ◽  
Short Life ◽  
General Paralysis ◽  
Generic Term ◽  
Fin De Siècle ◽  
History Of ◽  
Vexed Question

At the present time, when our fin de siècle knowledge of “general paralysis” enables us to recognize under that generic term many types of the disorder, and when the relation between it and syphilis continues a rather vexed question, little apology is needed for introducing to notice the following cases. They illustrate unmistakably some of the instances in which syphilis is solely responsible for what. Is termed by Dr. Savage” A process of degeneration which ultimately produces the ruin we recognize as general paralysis.”∗ Whatever may be hereafter formulated from the present evolutionary crisis in the history of the disorder there can be but little doubt that syphilis will be one of its most intimate and important relations. The story of its methods is briefly sketched in the following two short life-histories—in one asserting itself in the offspring of its victims by right of impure heredity, in the other carrying death direct into the vital centres by the force of its malignant virus.

scholarly journals On Apogamy and the development of Sporangia upon fern prothalli

1898 ◽  
Vol 63 (389-400) ◽  
pp. 56-61
Keyword(s):  
Life History ◽  
Point Of View ◽  
The Other ◽  
Normal Life ◽  
Other Hand ◽  
General Importance ◽  
Two Generations ◽  
History Of ◽  
Alternation Of Generations

The two most important deviations from the normal life-history of ferns, apogamy and apospory, are of interest in themselves, but acquire a more general importance from the possibility that their study may throw light on the nature of alternation of generations in archegoniate plants. They have been considered from this point of view Pringsheim, and by those who, following him, regard the two generations as homologous with one another in the sense that the sporophyte arose by the gradual modification of individuals originally resemblin the sexual plant. Celakovsky and Bower, on the other hand, maintaint the view tha t the sporophyte, as an interpolated stage in the life-history arising by elaboration of the zygote, a few thallophytes.

scholarly journals Effect of NaCl on seed germination in some Centaurium Hill. Species (Gentianaceae)

2007 ◽  
Vol 59 (3) ◽  
pp. 227-231 ◽  
Author(s):  
S. Zivkovic ◽  
M. Devic ◽  
B. Filipovic ◽  
Z. Giba ◽  
D. Grubisic
Keyword(s):  
Life History ◽  
Salt Tolerance ◽  
Seed Germination ◽  
Gibberellic Acid ◽  
White Light ◽  
The Other ◽  
Distilled Water ◽  
Nacl Concentration ◽  
History Of ◽  
Species Specific

The influence of high NaCl concentrations on seed germination in both light and darkness was examined in the species Centaurium pulchellum, C. erythraea, C. littorale, C. spicatum, and C. tenuiflorum. Salt tolerance was found to depend on the life history of the seeds. To be specific, seeds of all five species failed to complete germination when exposed to continuous white light if kept all the time in the presence of 100-200 mM and greater NaCl concentrations. However, when after two weeks NaCl was rinsed from the seeds and the seeds were left in distilled water under white light for an additional two weeks, all species completed germination to a certain extent. The percent of germination not only depended on NaCl concentration in the prior medium, but was also species specific. Thus, seeds of C. pulchellum, C. erythraea, and C. littorale completed germination well almost irrespective of the salt concentration previously experienced. On the other hand, seeds of C. tenuiflorum completed germination poorly if NaCl concentrations in the prior media were greater than 200 mM. When seeds after washing were transferred to darkness for an additional 14 days, they failed to complete germination if previously imbibed on media containing NaCl concentrations greater than 400 mM. However, the seeds of all species, even if previously imbibed at 800 mM NaCl, could be induced to complete germination in darkness by 1 mM gibberellic acid. .

The Odd Man Out in a Pioneer Cemetery at Seccombe Lake Park, San Bernardino, California

2020 ◽  
pp. 90-113
Author(s):  
Patricia M. Lambert
Keyword(s):  
Life History ◽  
Native American ◽  
Morphological Traits ◽  
The Other ◽  
European Ancestry ◽  
Latter Day Saints ◽  
Community Members ◽  
San Bernardino ◽  
History Of ◽  
The 19Th Century

In 1989, a pioneer cemetery associated with the 19th-century Latter-Day Saints colony in San Bernardino, California, was discovered during the construction of a baseball field. Among the remains of 12 individuals recovered from the cemetery were those of a young man of about 22 years, whose burial treatment differed notably from the other intact interments at the site. Unlike these coffin burials, Burial 5 was found in a sprawling position, apparently tossed unceremoniously into the grave pit. Dental morphological traits identified the genetic affinities of this man as Native American, perhaps a member of the local Cahuilla or Serrano tribes, whereas the other individuals appeared to be of European ancestry, an interpretation consistent with records kept by community members. A possible identity for this individual came from a journal account describing the shooting of an “Indian” by the local sheriff, who was then brought to the fort, died, and was buried before his fellow tribesmen arrived to determine what had transpired and perhaps to claim his remains. This chapter explores the identity and life history of this young man in the context of the history of the valley and the pioneer community in which he met his death.

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