GROWTH OF EGGS AND EGG-STRINGS IN NEPHELIS. 203 



tractions, which travel from behind forward. The contrac- 

 tion of the semi-circular fibres, whose extremities are 

 prolonged forward, would tend to push the contents of the 

 ovaries in the same direction. The ovarial tube could be 

 shortened on the mediad side by means of the longitudinally- 

 prolonged ends of the semicircular fibres ; while on the 

 rachal side, where these fibres are very little prolonged, the 

 shortening would be mainly effected by the contraction of 

 the longitudinal fibres. 



IV. The Germogen. 



If a fresh ovary be examined, there will be seen, besides 

 free egg-strings, a longitudinal ridge of cells, some parts of 

 which are beginning to take the form of egg-strings. The 

 entire ridge, which is a massive thickening of the lining 

 epithelium all along the inner surface of the rachis, may 

 be called the germogen.^ This is shown half-diagrammati- 

 cally in fig. 2, in section in figs. 4 and 11, and as partially 

 seen through the ovarial tunic in fig. o, ger. 



It is not strictly speaking a single ridge. It may be said 

 rather to be composed of a main median ridge, with smaller 

 ones on each side (fig. 4). But these ridges, or strings, are 

 very irregular, often diverging and uniting in such a manner 

 as to leave thin or open mesh-like spaces (fig. 3). Some- 

 times one of the smaller strings is continued into the larger, 

 or vice versa. The main string is irregularly cut here and 

 there into parts destined to become egg-strings (fig. 2). 

 The parts have no well-defined form or limits at first, but 

 assume gradually the form of egg-strings as they gain in size. 



When one of these, after attaining its full size, becomes 

 detached, the smaller strings may continue to grow, unite in 

 one string, and thus replace the detached portion. The 

 germogen is more massively developed where the calibre of 

 the tube is greatest. 



The germogen is simply a massive enlargement of the 

 lining epithelium, and, so far as I can learn, no other cell- 

 elements take any direct part in its formation. That the 

 loose fusiform epithelial cells actually give rise to germ-cells 

 there is no doubt. Transitional forms are met with abun- 

 dantly both in sections and surface views (fig. 3). But as 

 there is no membranous wall between the epithelial stratum 



1 I borrow this term from Balfour (' A Treatise on Comparative Em- 

 bryology,' vol. i, p. 14), who uses it, iu a restricted sense, to designate a 

 nucleated mass of protoplasm (syncytium) in which cell-outlines are 

 apparently absent, but which give rise to ova. I have taken the liberty to 

 apply che word to a case iu which cell-limits are more or less distinct. 



