ARGONAUTA ARGO AND THE HECTOCOTYLI. 8? 



to hold them for decicledl}'' independent animals, and every 

 future observer will be unable to avoid the same impression*. 



The circulation of the blood of the Hectocotylus, although its 

 course is only imperfectly known, is very lively and rhythmical. 

 It should be observed, that in detached arms of Tremoctopus a 

 rhythmical movement of the veins from the periphery to the 

 centre continued for half an hour after separation from the 

 body, although the animal had been dead for an unknown time. 

 The protracted contractility of separated portions of the Cepha- 

 lopoda, for example of the skin with the chromatophora, is also 

 already known. Yet in the whole male Argonaut the Hectoco- 

 tylus-arm was the part in which the reflex movement ceased 

 latest, since it continued to make apparently voluntary move- 

 ments for many hours after these had ceased in the rest of the 

 animal. How long the movement, and indeed the existence of 

 the Hectocotyli endure after their natural separation is altogether 

 unknown t, but probably for a considerable time, if copulation 

 be not effected ; if indeed they do not exist afterwards. 



The presence of the appendages described as gills in Hecto- 

 cotylus Tremoctopodis is very remarkable : since they do not 

 occur in other Cephalopod- arms and -fTec^oco^y/i, and since, like 

 the penis, they appear to become still larger in detached Hecto- 

 cotyli, it is to be concluded that the Hectocotylus in question is 

 originally intended to have a longer separate existence. But 

 the other Hectocotyli also are evidently by no means torn off 

 accidentally, but from the manner of their occurrence as well as 



* Verany mentions in comparison the gill-processes of Eolidse, which, when 

 detached, continue to move for many hours. 



t Since it is not easy to keep Cephalopoda with Hectocotyli in confinement 

 long enough, it will be desirable to pay particular attention in future to their 

 occurrence at particular seasons of the year. Verany obtained the Octopus 

 Carena at different seasons ; Kolliker obtained the Hectocotylus Tremoctopodis 

 in August and September pretty frequently ; that of the Argonaut again but 

 rarely. I found most Argonauts without Hectocotyli before the end of Sep- 

 tember, but at that time and in the beginning of October the majority of the 

 large specimens possessed them. In the end of July and the beginning of Au- 

 gust I obtained Tremoctopoda pretty frequently, and usually with Hectocotyli ; 

 on one occasion there were eight of the latter in one day. Subsequently the 

 Tremoctopoda occurred only singly, and no longer contained any Hectocotyli. 

 Hence the deficiencies in my account of the //. Tremoctopodis, since I erro- 

 neously expected always to obtain the same supply as at first. 



