150 VERANY AND VOGT ON THE HECTOCOTYLI 



to make out the last phase of this reproduction, when the ab- 

 normal arm, coiled up in a spiral, is enclosed within a vesicle, 

 from which it ought soon to make its exit and unroll outwards. 

 But it seems to us unquestionable that the arm is really repro- 

 duced in the interior of this vesicle, by budding from the 

 peduncle and raising up the skin covering the latter, which thus 

 in the end forms the vesicle enclosing the arm. The vesicle 

 which the little male of the Argonaut carries has exactly the 

 same relations ; it also contains in its interior the spirally coiled 

 Hectocotylus. 



Our observations as they stand could furnish only very scanty 

 indications as to the physiological function of these abnormal 

 arms of the males ; we have found in fact in these arms only 

 the ordinary structure of a cephalopod-arm terminated by the 

 tlabellum — a kind of tail fixed to one of the extremities, — and 

 by a cutaneous sac at the other extremity. This sac was inva- 

 riably empty in the individuals in which the arm was still fixed 

 upon its pedicle; it is formed, as we have just seen, by the 

 retroversion of the sac in which the arm is developed. But our 

 investigations, combined with the results obtained by MM. 

 Cuvier, Laurillard, KoUiker, and Siebold, solve the problem. 

 All these observers have examined the Hectocotyli when de- 

 tached ; all have noticed that in these separated individuals the 

 sac situated at the base was by no means empty, but that it was 

 filled by organs belonging to the generative apparatus. MM. 

 Kblliker and Siebold have also determined that this sac contains 

 a long folded spermatic cord, which is continued into an ejacu- 

 latory canal, having a harder pointed extremity, which these 

 writers call the penis, inasmuch as they believe the full sac and 

 its contents to be a true testicle, with the excretory and copu- 

 latory canals, which are ordinarily in connexion with this organ. 

 Now, our observations are formally opposed to this interpre- 

 tation. We have proved in fact that tl\e testicle is situated at 

 the bottom of the intestinal sac, and that it is constructed upon 

 the same type as that of other male Cephalopods. We have 

 shown besides, that this testicle is in relation with the pecuhar 

 excretory organs which fashion the seminal mass, so as in the 

 end to form a seminal machine — a spermatophore — of a very 

 complicated structure and of very considerable dimensions. 



