212 



servierung so unabhängig, daß ich bald zur Überzeugung gelangte, 

 daß diese Veränderungen des Protoplasma normale Entwicklungs- 

 vorgänge darstellen «. He speaks in another place, page 1 25, of »kleinen 

 polyedrischen Protoplasmastückchen, in welchen ich trotz aller Mühe 

 selbst an sehr schön gefärbten Praeparaten keinen Kern zu unter- 

 scheiden im Stande war. Ich muß deshalb die Zellennatur dieser Pro- 

 toplasmastückchen vollständig in Abrede stellen«. From these quota- 

 tions it is seen that he denies the cellular nature of the bodies within 

 the blastomeres, but oifers no explanation of their true nature. 



More recent papers by Brooks, Heider and Korotneff have 

 dealt with the relation between blastomeres and follicle. — 



Brooks, in 1893, confirmed Salensky's description of the com- 

 plex character of the young embryo, pointing out with the greatest 

 clearness that the follicle cells multiply very rapidly by amitotic 

 division, the resulting cells pushing in among the blastomeres which 

 for a long time remain few in number. 



He further showed that, as Salensky described, the migrated 

 follicle cells give rise to rudiments of the organs. He, however, took 

 issue with Salensky as to the ultimale fate of blastomeres and follicle, 

 claiming and clearly showing that in the later stages the follicle cells 

 composing the rudiments of the organs are replaced by true blastomeres 

 which give rise to the adult. He says page 27 «Stated in a word, the 

 most remarkable peculiarity of the Salpa embryo is this. It is blocked 

 out in follicle cells which form layers and undergo foldings and other 

 changes which result in an outline or model of all the general features 

 in the organization of the embryo. While this process is going on the 

 development of the blastomeres is retarded, so that they are carried 

 into their final position in the embryo while still in a very rudimen- 

 tary condition. Finally when they have reached the places they are 

 to occupy, they undergo rapid multiplication and growth, and build 

 up the tissues of the body directly while the scaffolding of follicle cells 

 is torn down and used up as food for the true embryonic cells«. 



Brooks' Figs. 1 and 2 Plate XLII, also Fig. 12 Plate IX, as w^ell 

 as his descriptions, demonstrate that the peculiar granular bodies seen 

 within the blastomeres at certain stages of development are not an 

 indication of the fragmentation or degeneration of the blastomeres, 

 but are nuclei of follicle cells that have been ingested and are under- 

 going digestion. This statement I have fully confirmed, as described 

 a few pages beyond. The amitotic division of the migrating follicle 

 cells confer the belief that they are on the road to degeneration, and 

 in the centre of the embryo there are found masses of such disintegrat- 

 ing cells. 



