TEE ANATOMY OF ALCYONIUM DIGITATUM. 377 



female colony collected in the month of April or May, several 

 of the mesenteries may be seen to bear close to their free 

 margins a group of small, clear, round or polygonal cells. In 

 the smaller groups the cells are all of approximately the same 

 size, but in some of the larger groups a few of the cells are 

 very much larger than the others, and contain two instead of 

 one nucleus (fig. 37). An examination of such a group with an 

 immersion lens shows that the nuclei are of two different 

 kinds, and take up the staining reagents differently. Some 

 present a well-marked nuclear membrane, and a number of 

 highly refracting chromatin granules giving the characteristic 

 appearance of a resting nucleus ; the others are perfectly homo- 

 geneous, staining deeply in hsematoxyliu, and presenting no 

 granules, nucleoli, or other structure. 



In the cases of the larger cells which present two nuclei 

 one of them is invariably of the former description, and the 

 other of the latter. 



The explanation of these facts seems to be that some of the 

 young ova — namely, those containing the homogeneous nuclei 

 — cease to grow, and divide at an early stage in their develop- 

 ment, and these become absorbed by the others which con- 

 tinue to grow. 



At the end of May, and in the months of June and July, 

 ovaries may be found on the mesenteries containing one or two 

 ova very much larger in size than the others, and in some of 

 these young ova may be seen partially disintegrated (fig. 38). 



There can be no doubt, then, that some of the young ova 

 formed in the ovary are swallowed up by the larger ones ; 

 others, however, simply degenerate, and their shrivelled 

 remains may be seen between the more mature ova. 



During the later months of the year the ova continue to grow, 

 and assuming a light yellow colour in August, they reach their 

 full size and deep red colour at the end of November or the 

 beginning of December. 



The ripe ova in the follicles of a female Alcyonium in 

 December are about 0*5 mm. in diameter, but I have noticed 

 a very considerable variation in the actual size of the ova 



