VIII.—The Oogenesis of Carcinus mœnas Penn., with Special Reference to Yolk Formation

1929 ◽  
Vol 56 (1) ◽  
pp. 157-174 ◽  
Author(s):  
L. A. Harvey
Keyword(s):  
Special Reference ◽  
Large Class ◽  
Growth Period ◽  
Yolk Formation ◽  
The Third ◽  
Laboratory Conditions ◽  
Yolk Nucleus ◽  
Nucleolar Extrusion

The present paper is the third of a series recording the results of investigations into the relations of the structures present in the oocyte during the growth period, particularly in their bearing on yolk formation. A Crustacean was selected for various reasons: firstly, as representing a large class about the oogenesis of which little is known, this in contrast to most other Arthropod groups which have been studied by several authors; secondly, in the hope that it would prove to have no yolk nucleus, and would exhibit nucleolar extrusion, a hope which has been fairly satisfactorily justified; thirdly, for the utilitarian reason that it is a common animal, easily obtainable, and able to live under laboratory conditions during considerable periods.

Memoirs: The Oogenesis of Calanus finmarchicus

1931 ◽  
Vol s2-74 (294) ◽  
pp. 193-222
Author(s):  
IRENE F. HILTON
Keyword(s):  
Golgi Apparatus ◽  
Growth Period ◽  
Growth Zone ◽  
Calanus Finmarchicus ◽  
Growth Phases ◽  
Yolk Formation ◽  
Primary Condition ◽  
Spherical Structures ◽  
Circular Chromosomes ◽  
Nucleolar Extrusion

Three regions can be recognized in the ovary: a multiplication zone containing oogonia undergoing mitosis, a synapsis zone containing the first formed oocytes in the prophases of the maturation division, and a growth zone containing oocytes in a series of growth phases with the nucleus in a ‘resting condition’. The oogonial nuclei contain two or three nucleoli--plasmosome and karyosomes. In the oocytes a single nucleolus is present; this is formed by the fusion of the plasmosome and at least one karyosome and is therefore an amphinucleolus. The chromatin in the oogonia and young oocytes is arranged round the periphery of the nucleus andis aggregated in knots (pp. 196-200). Nucleolar extrusion begins in the young oocyte and continues throughout the growth period. It is most marked in the young oocytes and in oocytes about to undergo maturation (pp. 200-3). In the older oocytes the chromatin is in the form of a tangled thread surrounding the nucleolus. Immediately before maturation this condenses and circular chromosomes emerge: these form tetrads (pp. 203-5). The mitochondria are present in the oogonia and very young oocytes in the form of a cap lying upon the surface of the nuclear membrane. The mitochondrial elements spread and multiply until they surround the nucleus as a ring; afterwards they disperse and are distributed evenly throughout the cytoplasm. They swell up and finally yolk-droplets appear in their place (pp. 207-11). Yolk-formation usually begins in half-grown oocytes, but is sometimes earlier. The formation of yolk-droplets begins at the periphery of the cell and proceeds inwards. It is suggested that yolk is formed by transformation of the mitochondria and the deposition in them of substances derived from the cytoplasm and the nucleolus. The cytoplasm is flocculent in the young oocytes, granular in the half-grown oocytes, and filled with fluid vacuoles in mature oocytes. It passes from a primary condition of oxyphily to basophily and finally back to a secondary oxyphil condition in mature oocytes (pp .211-13). In the young oocytes deeply-staining spherical structures were seen adjacent to the mitochondrial cap. From their appearance it is possible these bodies represent the Golgi apparatus, but Da Pano fixation failed to demonstrate them. In half-grown oocytes the apparatus was visible in the complex condition at one side of the cell. As growth proceeds it passes from a complex to a diffuse condition and in mature oocytes the Golgi elements are uniformly distributed throughout the cytoplasm (pp. 213-15).

Digestion in the tsetse fly Glossina morsitans Westw.: the effect of feeding field-caught flies on guineapigs in the laboratory

1967 ◽  
Vol 57 (3) ◽  
pp. 447-450 ◽  
Author(s):  
P. A. Langley
Keyword(s):  
Natural Environment ◽  
Environmental Conditions ◽  
Tsetse Fly ◽  
Rapid Loss ◽  
Glossina Morsitans ◽  
The Third ◽  
Laboratory Conditions ◽  
Effect Of Feeding ◽  
Blood Meals

It has been shown that adults of Glossina morsitans Westw. that have fed from a bait ox in their natural environment digest their blood meals more rapidly than others that have emerged and been fed in the laboratory, even when both are maintained under identical environmental conditions after feeding.In further experiments with G. morsitans in Rhodesia, flies caught in the field and fed in the laboratory were found to lose their ability to digest their meals rapidly. Measurements, made throughout three hunger cycles, of the rate of digestion, as reflected in the rate of excretion, of blood meals by field-caught flies fed on guineapigs in the laboratory showed that this was not significantly different from that of the normal, flied-fed flies during the first two hunger cycles but that during the third it fell to a level comparable to that of flise that emerged and were fed in the laboratory.It is concluded that whatever may be the events that condition the field flies to digest their meals rapidly in the natural environment, these are repeated with the ingestion of each meal, and that laboratory conditions cause a rapid loss of this greater digestive capability.

THE SMUTS OF THE GENUS CINTRACTIA PARASITING KOBRESIA SPECIES

1961 ◽  
Vol 39 (1) ◽  
pp. 155-164 ◽  
Author(s):  
Ilkka Kukkonen
Keyword(s):  
Special Reference ◽  
Spore Germination ◽  
Modern Concept ◽  
Short Account ◽  
Host Genus ◽  
The Third

In this paper the modern concept of infection by species of Cintractia is briefly discussed. Three species are treated, two of which, C. elynae Sydow and C. kobresiae Mundkur, are redescribed, and the third is recognized as new, C. lindebergiae n. sp. The spore germination of C. elynae is described and illustrated. A short account of the host genus Kobresia is given with special reference to the species attacked by the above smuts.

The Textual Tradition of Livy 21–25

1958 ◽  
Vol 8 (3-4) ◽  
pp. 161-164
Author(s):  
T.A Dorey
Keyword(s):  
Special Reference ◽  
The Third ◽  
Textual Tradition

The purpose of this article is to re-examine the more important extant manuscripts of Livy 21–25 with special reference to omissions and significant errors, and on this basis to try to establish their interrelationship in stemmatic form. A stemma for Books 26–30 has already been drawn up by Professor S. K. Johnson in O.C.T. vol. iv, but, since the tradition for those five books is slightly different from that of the first half of the third decade, it has seemed worth while to draw up a stemma for Books 21–25 independently. The manuscripts to be considered, and the sigla to be employed, are as follows:

Effects of delaying chemical fallowing in pasture rotations on pasture quality and wheat yield in the Victorian Wimmera

1989 ◽  
Vol 29 (1) ◽  
pp. 69 ◽  
Author(s):  
GJ O'Leary ◽  
RM Binns ◽  
TR Lewis
Keyword(s):  
Dry Matter ◽  
Yield Loss ◽  
Wheat Yield ◽  
Growth Period ◽  
Poor Quality ◽  
Yield Losses ◽  
The Third ◽  
Pasture Quality ◽  
Chemical Fallow ◽  
Conservation Method

The effects of delaying chemical fallowing in a pasture rotation on pasture quality and subsequent wheat yield were investigated at sites near Minyip and Charlton, Victoria, in 1983 and 1984. Three chemical fallows were commenced at different times and were compared with a conventionally cultivated fallow. The earliest chemical fallow was established, together with a conventional fallow, at the end of winter. The second chemical fallow commenced towards the end of the rapid spring growth period in mid-October (early hayfreezing), and the third in mid- November (late hayfreezing) on a grass-dominant pasture. The pasture in spring ranged from 51 to 72% digestible dry matter (DDM) but the quality declined to 42-50% DDM by the end of the fallow treatments in autumn at each site in both years. Weathering of the pasture over summer reduced it to roughage. In contrast to a conventional fallow, early hayfreezing of pasture reduced the yield of subsequent wheat crops at Minyip by 14% in 1984 and 26% in 1985. Late hayfreezing caused losses of around 35% in each year at Minyip. At Charlton yield losses were much lower with only 14% loss observed from late hayfreezing in 1985. Because the feed produced by hayfreezing was of very poor quality, hayfreezing cannot be recommended as a viable fodder conservation method as it could not adequately compensate for any yield loss.

The taxonomy of the order Isochrysidales (Prymnesiophyceae) with special reference to the genera Isochrysis Parke, Dicrateria Parke and Imantonia Reynolds

1977 ◽  
Vol 57 (1) ◽  
pp. 7-17 ◽  
Author(s):  
J. C. Green ◽  
R. N. Pienaar
Keyword(s):  
Special Reference ◽  
New Class ◽  
The Third ◽  
Unique Structure ◽  
The Family ◽  
Unique Status

The order Isochrysidales was erected by Pascher in 1910 to accommodate chrysomonads with two equal flagella. It was based on the family Hymenomonadaceae (Senn, 1900) and included such genera as Synura Ehrenberg (later shown to be heterokont and therefore incorrectly placed here; Hovasse, 1949; Manton, 1955), Wyssotzkia Lemmermann and Hymenomonas Stein. Papenfuss (1955) used the name in a similar sense but encompassing also the coccolithophorids, while those genera with two equal flagella and a ‘short third flagellum’ ((Prymnesium Massart, Platychrysis N. Carter, Chrysochromulina Lackey) were placed in the order Prymnesiales. Subsequently it was demonstrated that members of the Isochrysidales and Prymnesiales differ from other chrysomonads in that the two true flag-ella are smooth with no coarse hairs (‘mastigonemes’) and that the third appendage found in genera of the latter order is a unique structure, termed the ‘haptonema’ by Parke, Manton & Clarke (1955). On the basis of these observations, Christensen (1962) erected a new class, the Haptophyceae (now referred to by the typified name Prymnesiophyceae; Hibberd, 1976 a), to contain the two orders although Bourrelly (1968) preferred to retain them within the Chrysophyceae whilst recognizing their unique status by the erection of a sub-class, the Isochrysophycidae.

Memoirs: On the Relation of the Mitochondria and Golgi Apparatus to Yolk-Formation in the Egg-Cells of the Common Earthworm, Lumbricus Terrestris

1925 ◽  
Vol s2-69 (274) ◽  
pp. 291-316
Author(s):  
LESLIE A. HARVEY
Keyword(s):  
Golgi Apparatus ◽  
Nuclear Membrane ◽  
Lumbricus Terrestris ◽  
Yolk Formation ◽  
Central Mass ◽  
The Common ◽  
Yolk Nucleus ◽  
Earthworm Lumbricus

1. The yolk-nucleus is merely a mass of mitochondria. 2. The mitochondria arise as a cap of threads over the nucleus, and this cap grows in size and density, migrates away from the nuclear membrane and breaks up into its component mitochondrial threads. These threads become evenly spread throughout the cytoplasm of the cell. 3. The mitochondria are not clearly defined in the very young oogonia. 4. The Golgi apparatus consists of numbers of Golgi elements lying separate in the cytoplasm. There is never any attempt at concentration of these elements round one central mass. 5. The Golgi elements are probably little platelets or spheroids somewhat resembling blood corpuscles in shape. They are not rods. As fixed by Da Fano technique, each element is a little plate with a very lightly impregnating centre and a very heavily impregnating rim. 6. The Golgi elements may probably arise from the cytoplasm. 7. The nucleus contains two nucleoli; an early arising karyosome, homogeneous and solid in structure, and a plasmo some arising later This plasmosome is liquid in consistency and contains an argentophil core. The karyosome disappears before the oocyte is half grown, but the plasmosome remains in the nucleus while the egg remains in the ovary. 8. No visible nucleolar extrusions into the cytoplasm were observed. 9. Yolk probably arises from the cytoplasm; no direct metamorphosis of either mitochondria, Golgi apparatus, or nucleolus into yolk was observed.

How to Deal with Inequality: What Policymakers Should Know

2018 ◽  
Vol 10 (1-3) ◽  
pp. 11-24
Author(s):  
Montek S. Ahluwalia
Keyword(s):  
Developing Countries ◽  
Income Distribution ◽  
Special Reference ◽  
Emerging Market ◽  
Corrective Action ◽  
Fourth Section ◽  
The Third ◽  
Center Stage ◽  
Emerging Market Countries ◽  
Select Group

High and rising levels of inequality have become a hot topic of discussion in both industrialized and developing countries in recent years. In this article, the author focuses on four different aspects. The first section provides a brief commentary on how inequality has moved to the center stage and different elements that drove this process in industrialized and developing countries. The second section presents an assessment of the available data that suggest what has happened to income distribution in a select group of industrialized and developing countries. The third section discusses some of the determinants of income distribution, which we need to understand if we want to reduce the degree of inequality. The fourth section discusses the scope for corrective action in this area with special reference to emerging market countries.

The Algebra of Dimension-Linking Operators

1965 ◽  
Vol 8 (2) ◽  
pp. 203-222 ◽  
Author(s):  
R. H. Bruck
Keyword(s):  
Group Theory ◽  
Special Reference ◽  
Mathematical Society ◽  
Summer Institute ◽  
Burnside Problem ◽  
The Third ◽  
Australian Mathematical Society ◽  
Suitable Definition ◽  
Definition Of ◽  
Restricted Burnside Problem

In the course of preparing a book on group theory [1] with special reference to the Restricted Burnside Problem and allied problems I stumbled upon the concept of a dimension-linking operator. Later, when I lectured to the Third Summer Institute of the Australian Mathematical Society [2], G. E. Wall raised the question whether the dimension-linking operators could be made into a ring by introduction of a suitable definition of multiplication. The answer was easily found to be affirmative; the result wasthat the theory of dimen sion-linking operators became exceedingly simple.

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