306 OVARY AND INTRA-OVAEIAN EGG IN TELEOSTEANS. . 



the nucleoli are few in number but large in size. Whenever the 

 nucleoli atrophy and disappear there is no prospect of the egg ever 

 coming to maturity. Without nucleoli it cannot even form its dark 

 ring of protoplasm. It seems to me that under these circumstances 

 I cannot agree with Scharff and Will^ who unite in attaching no 

 morphological significance to the nucleoli. 



It is truCj as the former says, that they are sometimes present 

 and sometimes entirely absent, but I have never found any evidence 

 to show that without nucleoli ova of Teleosts can ripen. I am, in 

 fact, inclined to regard the nucleoli as of the highest importance, the 

 fountain-head of the entire system. 



III. The Minute Ova. 



The only point of interest in studying the minute ova is their 

 origin, since their average condition is one of inactivity. 



After spawning, the enveloping membrane of the ovary sends out 

 fibrous prolongations in an irregular manner towards the centre of 

 the organ. These form leading lines of support in the loose arrange- 

 ment of the ova. As offshoots from these the supports of the 

 lamellge are formed. In different species the lamellae run in different 

 ways, e. g. longitudinally in Pleuronectids, transversely in Gadidss, 

 and obliquely in the mackerel. With few exceptions (Murgenidge and 

 Salmonidae) the inner boundary line of the lamellae is composed of 

 germinal epithelium. 



It has been stated by Brock (11) and Kolessnikov (12) that each 

 forming ovum is produced from one single epithelial cell. In addi- 

 tion to this the appearances presented in my sections lead me to 

 believe that, in the case of the common dab at any rate, ova are also 

 formed in another manner. I find small nests of cells, collected at 

 intervals, inside the germinal epithelium, and from watching them 

 am satisfied that while perhaps in the majority of instances ova are 

 formed from single cells only, they are also formed from these nests 

 of, it may be, ten or twelve cells. Fig. 9 shows a growing lamella 

 at this stage, where a few of the nests are seen (w). They are 

 quite separate from all other epithelial cells, and shortly begin to 

 show a disposition to coalesce. The outlines of the individual cells 

 disappear, and the mass, beginning to stain deeply, assumes a very 

 dense appearance. 



A collection of deeply stained bodies, very similar to the nuclei 

 of the cells or the amalgamated nuclei, then make their appearance, 

 and take up the position of nucleoli in what must now be called the 

 ovum. Meanwhile there are other epithelial cells collecting in all 

 the spaces of the ovary — often showing division. These grow round 



