OBSERVATrOXS ON FRESH-WATER POLYZOA. 125 



sich ZU einen Follikel formiren. Die Eizelle maclit einen reo-elimiss- 

 igen Fui-clinng8proces.s durch, dessen Resultate eine solide M(^ruhi 

 ist. Wie man sieht, wird also auch durch diesen F urchungs Vorgang 

 die Knospennatur der Statoblast widerlegt." Hence he concludes : 

 "Die Statohlasten sind als parthenogenetische Wintereier aufzufjis- 

 sen welciie sich im Gegensatze zu befruchteten Eiern am Funiculus 

 entwickeln." I did not find this view corroborated l)v facts. 

 Neither the thickening of the funicular epithelium nor aii "Eizelle," 

 which to judge from his figures must have beeii several times lare'er 

 than any ordinary cell of the funiculus, couhi be found. 



On the contrary, what I have seen in PectinateUa fidatinom 

 leads me to the conclusion that each statoblast originates from at 

 least eight cells of separate derivation. Where the}' come from is a 

 qiiestion which I cannot answer from direct observation. However, 

 that it receives no element from the entoderm is evident from the 

 fact that where there are many statoblasts in the same funiculus, the 

 older ones always lie nearer the stomach, completely shutting np the 

 ]iassage. The question then reduces itself to whether the original cells 

 are derived from either the funicular wall (mesoblast) or the (mter layer 

 of the endocyst (ectoblast) at the point where it bounds the funicular 

 cavity below, or from both. As will be seen later on, the intrastato- 

 blastic development of a polyzooid essentially agrees with the process 

 of development liy budding, differing only in such points as are 

 necessitated by the mechanical conditions of each case. Wes hindd then 

 expect similar elements in the " anläge" of a statoblast as in a bud. that 

 is. both the funicular wall and the outer layer of the endocyst should 

 a priori give their contingents to form a statoblast. The correctness 

 of this assumption is proved by the observations of Braein (Zool. Anz. 

 1889.). According to this author, the primitive statoblast consists 

 of two kinds of cells, which are genetically different, one deriving 



