128 J. T. CUNNINGHAM. 



no body separate from the germinal vesicle, but there is 

 frequently to be detected a cap of differentiated cytoplasm 

 applied to the external surface of the membrane of the ger- 

 minal vesicle. There can be no doubt that this cap of 

 cytoplasm, which is granular and deeply stained, is the earlier 

 condition of the vitelline nucleus. The two stages described 

 are represented in fig. 21, as they are seen in two contiguous 

 ova in one of the sections. The smaller ovum is "037 mm. 

 in diameter, the larger '098 mm. 



In a previous paper (20) I have briefly described the relations 

 of the vitelline nucleus in the ova of the common pipe-fish, 

 Syngnathus acus, so far as they can be ascertained by the 

 examination of fresh material. Although I have not been 

 able to trace the history of the ova in this form completely, 

 I am able, after examining several ovaries by means of sections, 

 to confirm and extend the results previously recorded. The 

 ovary of Syngnathus is a cylindrical tube of narrow diameter, 

 and its structure is remarkable on account of the narrow limits 

 to which the proliferating germinal epithelium is confined. 



There is but one germinal lamina which extends along the 

 ovarian tube lengthwise, and germ-cells are present only at 

 the extreme edge of this lamina. The ova, when separated 

 from the germinal epithelium, pass in succession towards the 

 base of the lamina, and then into the wall of the ovary as 

 they grow larger. At least, it is certain that the largest and 

 most advanced eggs are found in the wall of the ovary, and 

 that the free projecting lamina contains a row of eggs diminish- 

 ing in size, and descending in degree of maturation towards 

 the extreme edge. The arrangement may be partly or wholly 

 due to the growth of the germinal lamina outwards, and not 

 to the passing of the ova inwards, as the fact that the oldest 

 parts of a herbaceous plant are nearest to the root is due to 

 the fact that growth takes place at the apex. I have not 

 attempted hitherto to determine positively the mode of growth 

 in the ovary, but the resulting arrangement is that represented 

 by the section of the germinal lamina shown in fig. 22. The 

 section from which the figure was taken was prepared from 



