ii8 



BIOLOGIC A L LECTi'RES. 



cell, while in Stentor a whole crown of such organs is formed 

 without any division into cells. Could one ask for a clearer 

 demonstration ? Are we not forced to conclude with Gruber 

 that " /unvvvcr g-irnt the dijfcrciicc bctivccn an iiifusoritiui aud a 

 highly organized auinial, it eaiinot be a qualiiati^'e one. Wc 

 can assnnie that the same vital elements serve in both as the 

 fonndation, only in ever new combinations. This kinship 

 declares itself very clearly in the correspondence of many organs 

 of the infusoria ivith those of the higher organisms'' (I.e. p. 1 6). 



C(^^^ 



Fig. 3. 



./, ■•Corner cell" of Cyclas cornea. B, Section of three cells 

 letters as in V\^. 2. 



Other 



" So finden wir," says Gruber, " in einem Thiere, das 

 schon hoch auf der Stufenleiter der vielzelligen Organismen 

 steht, dieselben Grundelemente wieder wie in dem einzelligen 

 Infusionsthierchen. . . . 



" Wieder und wieder der Beweis von dem gottlich einfachen 

 aber auch gottlich gewaltigen Gesetze der Einheit der Xatnr'' 

 (p. 18). 



The entoderm of Dicyema illustrates one or two points of interest in this 

 connection. We have here an organ in which, as often iiappens, in parasitic 

 degradation, cell-formation has been dispensed with. I'lie entoderm remains 

 throughout life as a single cell, and the whole process of reproduction, for both 

 kinds of embryos, is carried on /// t/ie hoJy of titis cell without any cellular organs 



whatever. 



In one respect this unicellular organ, which was undoulnedly (juce multicellular. 



