471 



measures 150jul in length the nuclei of the surrounding follicle 

 cells measure 17/x in diameter. Although the egg is living 

 at the expense of the nutritive ceils, these also grow greatly 

 in size; it is difficult to detect their cell boundaries, but they 

 show the same disproportionate growth between nucleus and 

 cytoplasm, e.g., wh^n the egg measures 18/a in length, the 

 nutritive cells measure about 11 fj. in diameter; their nuclei 



We see, then, that the follicle cells and nutritive cells 

 undergo certain characteristic changes as the ovum develops; 

 they remain of a fixed size for a time, or increase in size 

 more or less rapidly, but their growth is not proportionate 

 to that of the ovum. Their nuclei, on the other hand, grow 

 rapidly in size, and the rate of increase of these is much 

 greater than that of the cells containing them. 



Now it has been clearly shown by Morgulis (1911) that 

 the body cells of salamanders undergo during starvation a 

 rapid diminution in size; also that the nuclei themselves 

 become smaller, but that the rate of diminution in these soon 

 becomes less than that of the cytoplasm. As a result the 

 ratio of nucleus to cytoplasm is much greater than in normal 

 cells. Exactly how this is to be interpreted is difficult to 

 say. It may be that the nucleus ha® greater powers of 

 resistance to starvation than has the cytoplasm; on the other 

 hand, it seems much more correct to assume that there is an 

 intimate relation between the cytoplasm and nucleus, and that 

 the condition which we find in a starved salamander cell is 

 such as will enable it to exist the better under these changed 

 conditions. And although this phenomenon is by no means 

 universal among starving cells, still it seems to suggest that 

 a great increase in the nucleo-cytoplasmic ratio is a sign 

 that the cell is living under certain adverse conditions. 



It is in this way, possibly, that the remarkable changes 

 in the nucleo-cytoplasmic ratio, undergone by the nutritive 

 and follicle cells, is to be interpreted. That the nutritive cells 

 nourish the ovum is universally recognized; that the follicle 

 cells nourish the ovum is more difficult to prove. However, 

 the fact that the latter cells undergo this same nuclear change 

 is a curious piece of evidence in favour of this view. 



Considered in this light, the nutritive and follicle cells 

 exhibit the interesting combined effects of nourishment and 

 starvation. Their growth in size is due to their receiving 

 a large supply of nourishment; the preponderance in the size 

 of the nucleus is the result of the parasitic habit of the ovum. 



The ova continue to grow rapidly, reaching at the end 

 of pupal life their mature length of about SOOjut. They are 

 ready for fertilization immediately the wasp emerges. 



