MUSEUM OF COMPARATIVE ZOOLOGY. 95 



filaments placed alternately and running across between adjacent tu- 

 bules. These were thickest next to the tubule, and rapidly tapered to 

 very fine threads. In his opinion, the method of the formation of the 

 tubules might be made out during the winter. " The question is, whether 

 each of the tubes arises from a single cell, which becomes open, or whether 

 the tubes are originally inter-cellular, and whether their walls result from 

 the rem?iants of several cells in contact with each other." 



A similar condition is maintained by Midler for Acerina vulgaris, but 

 the membrane in this case was much thinner and the tubules conse- 

 quently shorter. 



Lereboullet ('54, pp. 242, 246) also discovered independently, per- 

 haps even before Miiller, 1 that there were in the perch what he called 

 hollow closely interlaced piliform appendages (also called stiff curved 

 filaments), which traversed the whole thickness of the shell, and to which 

 he attributed the agglutination of the eggs into a network. He also saw 

 besides these the much finer pore-canals. 



In regard to the chemical nature of the capsular membrane, it was 

 maintained by Von Baer ('35) and by Leuckart ('55, p. 260) that it 

 was an albuminoid substance. Kolliker ('58) called it gelatinous, but 

 His ('73, p. 15) proved that it at least closely resembled chondrin, and 

 consequently claimed the right to call it a cartilage capsule. 



Reichert ('56, p. 93) was not able to add much to Muller's account of 

 the structure of the capsular membrane. Concerning its origin he was 

 at first inclined to believe that it resulted from [a metamorphosis of]] 

 cells ("aus Zellen hervorgegangen "), and therefore to regard it as a pro- 

 duct of the membrana granulosa. This conclusion was strengthened by 

 finding the granulosa composed of cylindrical cells in the case of Esox, 

 and that when this membrane appeared in the perch the granulosa cells 

 had disappeared ; but subsequently, finding that the follicular cells in 

 the perch were round, and not finding any transitional stages from the 

 epithelium to the membrane, he was compelled to leave the question 

 unsettled. Reichert was certainly looking in the right direction, and 

 evidently very near to a fair settlement of the question. 



It remained for Kolliker ('58, p. 90) to confirm this supposition of 

 Reichert. He found that in February the capsular membrane had a 

 thickness of 45 /x to 75 /<,. The tubules, he says, are formed by the 

 outgrowth of the epithelial cells of the follicle, so that the jelly which 

 joins them can only be a substance secreted by these cells. These so called 

 tubules were after all not hollow structures (" noch keine deutlichen 



1 See Kolliker ('58), p. 81, foot-note. 



