EARLY DEVELOPMENT OF GRAFFILLA. 



that this viviparity may be seasonal and parallel with the pro- 

 duction of summer eggs, as is known to be the case in some of 

 the Me-o-i,,mata. Certain facts in Graffilla might seem to 

 indicate that what we have de-cribed are the conditions peculiar 

 to a period r,f s Um mer egg production. Thus the thin shell i- a 

 di-tinctive characteristic of a typical >uniiner egg (Siibitanei< 

 and the well de\ eloped unicellular >hell--lands suggest at lea-t 

 that these organs could function later, if the species entered 

 ii|on .1 period . ,f winter egg production (I >auen -ier . However, 

 in the ab-eiice ot any proof that winter eggs are produced, and 

 in the li'Jit ot the fact that several of the female reproductive 

 ins s| 1( ,\v a rudimentary or degenerate condition, we are 

 inclined to belie\e that what we have described is the e\clu-i\e 

 method of reproduction in this species. The pr--ence ot shell- 

 vi 1. 1 nd-, ot a rudimentary receptaculum semini-, and of an indefi- 

 nite uterus and ducts, instead of indicating that t he species could 

 Liter produce \\ inter eggs, may and probably do, sj-nifv the i 1 

 relationship of this species to the other member-, of the -enus in 

 \\hich ilii--e -tructures are functional. 



( )f the halt do/en species of Graffilla described iii the literature, 



'llifxirii appears tO COme Closest, in its gent r.il arrangement 



of or-. m~, to d. Miiricicohi. It also shows -oine -imilarity to 



Ha iniiolii. but dilters primarily from the latter in ha\in^ the 



lital poie situated further back on the bod\ . 



In conclusion, we should like to point out. as a result of our 

 studies on this animal, the necessity of exercising mv.u precaution 

 in concluding that a ^iven species exhibit s p, ,|\ embr\ on\ . I n- 

 ( lou bit i IK the phenomenon of polyembryonj will, in the future, be 

 found to be much more extensive than we ha\e Mi-pecied; but 

 before coming to anv delinite conclusions, the in\e-ii-aior should 

 trace the de\elo].inent back to the fertili/eil . 



LITERATI ki 



Bbhmig, L. 



'86 1 ntct-iu luini;' n uln-r rhabdocoele Turbellarien. I. Das genus Graffilla. 



/fit. mi \\ ISB. /.>1.. H.I. 43. 

 Francotte 



'97 R- In !. In - ~iir la maturation i-lu-/ l.> I'nly<-l;ile<. Mem. Cour. A 

 Belg. 



