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. J O U K N A L 



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KOYAL MICROSCOPIC /VL SOCIETY. 



MARCH, li)21. 



TBAN8ACTI0NS OF THE SOCIETY. 



I._C0XTRIBUT10NS TO THE STUDY OF THE 

 OOGENESIS OF PATELLA. 



By Reginald James Ludford, B.Sc.(Lond.), F.R.M.S., 

 Zoology Department, University College, London. 



(Read February 16, 1921.) 

 Two Plates. 



Introduction. 



Recent work on oogenesis lias shown that the part played in tliis 

 process by the various cytoplasmic inclusions varies considerably 

 in different organisms. Mitochondria and the Oolgi appai^atus 

 have been shown to be present in nearly all animal cells studied 

 by modern methods ; and although there is occasionally some 

 doubt about the mitochondi'ia, both categories of cellular inclusions 

 are probably present in the undifferentiated germinal epithelial cells 

 from which ova and spermatozoa arise. In the complex series of 

 changes which take place during oogenesis the mitochondria increase 

 in number by fission and spread throughout the cell, and either they 

 remain unaltered in the mature ovum, as in certain Molluscs, or a 

 part of the mitochondrial content of tlie cell may be converted into 

 yolk bodies, as has been described in Ascaris (8),* Apanteles (4), 

 Eana and Lepus (7). In young Ascidian oocytes, according to 

 Hirschler {9), there is present a granular body, the chondriome, 

 from which is formed the mitochondria and also yolk nuclei. 



The Golgi apparatus of most animals in the youngest oocytes 

 is excentrically disposed, and consists of a number of rods or 



* The italic figures within brackets refer to the Bibliography at the end of the 

 paper. 



B 



