2d2 MORGAN. [Vol. IV. 



have found the test-cells forming) Davidoff believes the nucleus 

 to constrict off portions of itself which he calls buds (Knospen 

 Nucleogemmas, Kernknospen). These nucleogemmse migrate to 

 the periphery of the egg, and divide in many cases into smaller 

 nuclei, although no mitotic, nuclear fig2ires were found, and the 

 more peripheral nuclei stained more deeply than the more 

 central bodies. At a later stage of development (which corre- 

 sponds to a stage in which I have found the test-cells constricted 

 off from the follicular zone) Davidoff finds these peripheral 

 nuclei — nucleogemmas — to imdtiply by mitotic division. At 

 the stage when these karyokinetic figures are found, the pe- 

 riphery of the egg is colored more intensely than elsewhere. 

 Then the peripheral protoplasm of the ^%% divides itself into 

 cells with a nucleogemma in each such cell. 



Next follows a short account of the formation of the ova of 

 Fritillaria. The young ovary contains a few cells which he 

 calls ooblasts. They subsequently fuse, forming a syncytium. 

 From the nuclei of this syncytium — the karyoblasts — there 

 are budded off nucleogemmae which, after cutting off some of 

 the protoplasm of the syncytium, form the true ova. Comparing 

 the Ascidian with the Appendicularian developments, Davidoff 

 concludes, " Bevor wir indessen diesen Vergleich mit Erfolg 

 durchfiihren konnen, mussen wir uns die Frage vorlegen, was 

 denn das Ei der Ascidien selbst ist. Nach allem Gesagten 

 kann dasselbe nicht mit einem Ei der Fritallaria homologisirt 

 werden. Wir mussen viel mehr zuruckgreifen und sehen, ob 

 wir die Ascidien-Eier mit einem der Ooblasten des Fritallaria 

 — Ovarium vergleichen konnen. . . . Wir konnen also jetzt 

 mit Recht den Schluss ziehen, dass das Ei der Ascidiefi eigetit- 

 lich kein solches in gewdUmlicJien Sinne ist. Es ist vielmehr ein 

 Ooblast, welcher erst Eier producirt." These eggs are the 

 test-cells, or, as Davidoff concludes to call them, abortive eggs. 

 By some such complicated explanation with its complicated 

 terminology, he attempts to homologize the formation of the 

 ova in the Appendicularian and Ascidian. Such a process of 

 formation of the Ascidian Q.gg seems so highly improbable in 

 itself, and the method by which the ooblast divides into abor- 

 tive eggs and egg proper is so out of the usual course of events, 

 that it must take exceedingly strong evidence to support such 

 a position. On the other hand, the increase in area of the follic- 



