ARGONAUTA ARGO AND THE HECTOCOTYLI. 59 



This could be seen partly upon opening the capsule, partly 

 from without during the movements of the Hectocotylus. The 

 appendage not only twisted about in the capsule, but crept al- 

 ternately out and in, so that even the thin part of the sucker- 

 bearing body, as far as it would go, became hidden in the cap- 

 sule. The Hectocotylus then crawled about in a very peculiar 

 manner w ith this inserted part, which formed about the middle of 

 the body, directed forwards. On the other hand, if the Hecto- 

 cotylus were disturbed by touching, it not unfrequently drew its 

 appendage quite out of the capsule, and could then be no longer 

 distinguished from the first form which has been mentioned. 



It appears then, that the appendage makes the pigmented 

 capsule its residence either from being accustomed to its pre- 

 vious imprisonment in the sac, or as a sort of presentiment of its 

 proper position *. 



The exceptional occurrence of seminal canals in the capsule 

 of Kolliker's Hectocotylus is explained, if we consider the route 

 which the semen must take to be poured out. 

 I Kolliker has exactly described the course of the vas deferens 

 between an aperture in the neighbourhood of the point of the 

 appendage and a thick silvery sac which lies under the pigment- 

 capsule. He called that sac a penis, or finally, vesicula semi- 

 nalis ; assuming that the semen passes out of the capsule 

 (testis) along the appendage, then into the ductus deferens 

 along the back, and finally out of the silvery sac at the thick 

 end of the Hectocotylus. 



However, in the most free Hectocotyli, and even in the 

 largest of the included ones, we find this sac completely filled 

 with semen. Sometimes this distension extends into the ductus 

 deferens to a greater or less extent, and evidences itself to the 

 naked eye even, by an intense white streak along the back and 

 appendage of the Hectocotylus. Lastly, on one occasion a Hec- 

 tocotylus passed a whole coil of a thread, about '06 of a line thick 

 and consisting of spermatozoa, from the aperture of the append- 

 age, and the thread remained attached to it, so that the appear- 



* Considering the occurrence of gills in Hectocotylus Tremoctopodis, we 

 might ask whether that form developes a digestive organ, for which Cuvier 

 took the capsule in //. Oclopodis. At present however we have no evidence 

 upon the point. 



