290 MR. F. E. BEDDARD ON THE L'^^*') 4, 



lopment o( Bomhinator^ ; but there are certain facts adduced by 

 Gotte which require to be recorded in Lepidosiren before my opinion 

 can be expressed without hesitation. Gotte observed a fusion of 

 the nuclei as well as of the protoplasm of the primitive germinal cells ; 

 I have not been alile to detect any such fusion in Lepidosiren ; 

 on the other hand it is difficult to interpret my results so as to 

 regard these ova as equivalent in each case to a single cell. As 

 already mentioned, the series of ova between the earliest stage where 

 a mass of follicular cells contained a nest of primitive germinal cells, 

 and the latest stage when the ovum was surrounded by a single 

 layer of follicular cells and separated from them by a delicate mem- 

 brane, is fairly complete ; there seems to be no doubt that somehow 

 or other the numerous primitive germinal cells of the nest result in 

 the formation of one ovum. There were no si^ns of the separation 

 of any of these cells to form a number of different ova, as Balfour 

 has described in Scylliiim ; none of the central cells became larger 

 than the rest, and the follicular epithelium, which was specialized as 

 such in the earliest stage observed, showed no breaks in its continuity 

 at any time ; if the ovum really represents one of the primitive 

 germinal cells, the rest serving as pabulum, it is remarkable to find 

 that this cell shows no difference in size or structure from the rest 

 as development proceeds. 



The appearance of a fusion of some of the cells, which strongly sup- 

 ports my view of the case, is illustrated in Plate XXVIII. fig. 7, ^ ; the 

 homogeneous mass depicted in that figure contains a few nuclei, and 

 occasionally a certain amount of the cell-protoplasm still unaltered 

 centrally, but peripherally shading off into the supposed protoplasmic 

 mass. It might perhaps be supposed that this peripheral darkly- 

 staining mass is really due to the coagulation of some fluid substance ; 

 but in that case the appearance of nuclei, w ithout any cell-protoplasm 

 in its interior, would have to be explained, and more particularly the 

 presence of yolk-particles which seem to be formed by its meta- 

 morphosis. 



For the present I am unable to say any more about the develop- 

 ment and maturation of these ova ; the most important matter that 

 requires further investigation is the mode of origin of the germinal 

 vesicle ; but there are obviously other points that remain to be dis- 

 covered before the whole history of these ova can be cleared up. 



It might be supposed that the facts described in this section do 

 away with the necessity of any immigration of follicular cells ; the 

 yolk has been shown to originate largely in the primitive germinal 

 cells, and many of the free cells remaining in the interior of the ovum 

 during later stages are no doubt derived directly from the primitive 

 germinal cells. In the earlier stages the follicular cells, although 

 forming a distinct layer, are not individually very different from the 

 central cells of the nest ; hence their proliferation and migration 

 inwards is not surprising. It has been already mentioned that the 

 yolk commences to be formed very early in the foUicular cells as 

 well as in the central cells, so that the former evidently takes a 

 ' ' Entwickeliuigsgesc'hicble der Unke.' 



