been manifested. With tliis accumulatioii of the germinal piatter.jthe 

 corresi)onding- pole of the egg also becomes heavier, /., 



^Tnits singular progressive movement the germinal lay^r is observed 

 tojl)ecorae thicker at the lower thau at the upper pole of the e^g, and 

 tp' bulge up wurds into convex elevations on its inner surface next the 

 yelk. 'This migration proceeds until the yelk at the upper, pole is 

 almost exposed, as in Fig. G, which shows the relation of the germinal 

 matter to the yelk one and a half hours aftjer impregiig^tipii. While there 

 are no oil spheres present to buoy up the eggs^ as in tlie mackerel and 

 moou-fish, the specific/ gravity of the germinal, ina,tter/is^r;eater thai^ 

 that of jthe yelk, so that it always assumes a positiOin on t;hg lower side 

 of' the yelk. Should the egg be turned round f^o as to bring the disk 

 uppermost, the yelk will be gradually turned t»y the gravity of the disk 

 iinfil the latter regains its nethermost position. I) uripgrits- migration 

 the germinal i)rotoplasm eventually arranges itself in radiating bands, 

 which sometimes anastomose, and all trend towards and join the edgp 

 of the inciiiient disk belov^. Later these bands develop nodes or e^i- 

 Ta'rgements, prn, along their courses, as shown in Fig. 7, and pour their 

 substance into the disk, which is now defined three hours and forty min- 

 utes after impregnation. If a granule in one of these bauds is watched 

 for a time it will be noticed that it exhibits a more or less decided pro- 



gressive movement. . . . . ,,., , r , ,»o ,. r. r 



At the time the disk is defined its inner surface at first presents irreg- 

 ^ilar rounded elevations, which gradually subside, when the under S|ide 

 ofthedisk becomes flat. Then the outer surface of the disk is elevated 

 iiifo one or more large rounded, prominences, which in like manner ev^eu: 

 tually disapi)ear. These are some of the aiiioibal phenomena alreadi"" 



It IS very important for us to make a distinction here between the 

 mode of formation of the sermiual disk of the cod and that of the Clii- 

 peoidsj.as worked out by Kupfi'er and myself, and of ymcot, as described 

 iiyj Van Bambeke. It would appear that we concur in the opinion that 

 ill !the latter more or less protoxdasm destiued for the development of the 

 germinal disk is derived from the pester of the vitellus^.iiitp which, as 

 ihay be seen in the ova of Alosay Ctupca, and Pom<dohi(s, the external 

 germinal layer sends i)rocesses which in the shad and branch herring 

 Took like hyaline ropts passing down amongst the yelk spheres. At 

 a .later stage of development this arrangeiuent seems to ^ disappear, 

 ttiid tlie yelk spheres, although still evidently involved in a. mesh^vork 

 of germinal matter, dp not have the same amount of the latter insin 

 .nated bet:ween them as at first Jn the vicinity of ^t^ ger; 



imjiai (Jisk. On the other liand^, ip tli^' eg^gf^'fO^^^fye^f^w^,^ .<^- 



lm(m,ij la cafe, ixnd Parcphq)pns, the germinal matter forms a distinct 

 outer coating Qv^r the yitellus, and .these lorms .dp npt^h|ive any dis- 

 ^tiuqtly marked yelk spheres^ as ' m AJos^i. 'w^MM'-^^i9^r^ protp- 



