3o8 JOURNAL OF CONCHOT-0(n'. 



SOME REMARKS WITH RESPECT TO 



MR. WOTTON'S PAPER ON THE LIFE-HISTORY OF 



ARION ATER. 



By dr. HEINRICH SIMROTH, Gohi.is eei Leipzig. 



(Read before the Conchologicnl Society, iNIay 3, 1893"). 



The accuracy of keeping and breeding Arion afcr to a state of 

 maturity is admirable and Mr. Wotton is to be congratulated 

 sincerely on his success. Every one who has taken pains with 

 the subject will know that this species commonly endures in 

 captivity for a long time without getting ripe. My own ex- 

 periences reach only over few months. But the late Baron 

 von Maltzan told me that he had kept Arion empiricomiu for 

 several years, during which time the animals increased very 

 slowly. Evidently the species needs much understanding of 

 its habits. 



But another point seems to me less certain. That Arion 

 afer propagated when isolated from its youth is very interesting; 

 nevertheless, INIr. Wotton's interpretation of the fact is perhaps 

 to be doubted. As the author thinks, the act depends on self- 

 fertilization. Possibly the eggs were developed without impreg- 

 nation. At least, the question is to be kept open. We have 

 examples of self-copulation and those of propagation under 

 isolation. Already C. E. von Baer saw a Limnfea introducing 

 its penis into its vulva. This is presumptively possible only 

 where the male and female orifices are separated. On the 

 other hand, Braun, e.g., observed the propagation of Limncea 

 under isolation from the egg-state, without deciding, I think, 

 whether it was self-fertilization or parthenogenesis. Plate has 

 lately described a channel between the penis and the vagina in 

 some Testacellfe^, and he brings forward the opinion that the 

 arrangement would permit self-fertilization if the occasion of 



1 L. Plate, ' Studien liber opisthopneumon. Lungeiischnecken.' Zool. Jahrb., iv., iSoi. 



J.C, vii. July iSq:;. 



