62 MULLER ON THE MALE OF 



included Hectocotyli, the coils of a thread of 0'06-0'08 of a line 

 in diameter, consisting of perfect spermatozoa. I have not seen 

 the aperture of this organ, stated to exist by Kolliker at the ex- 

 tremity of the thick end of the Hectocotylus. If the semen be 

 actually passed out of the testis into the capsule, such an open- 

 ing must exist at one period or other ; but it probably becomes 

 closed behind the deposited semen before the detachment of 

 the Hectocotylus takes place. 



The spermatozoa of the Argonaut consist of a very delicate 

 thread, at one of whose ends is a somewhat thicker fusiform 

 body. They are therefore analogous to those of Tremoctopus, 

 but smaller, since they measure, as we see especially in the 

 bundles, only 0'08-0'09 of a line in length, of which we may 

 consider the body to form O'Ol of a line. In general the bodies 

 lie grouped together, and from them the threads pass nearly 

 parallel, like the cilia of a colossal ciliated epithelium. On one 

 occasion almost every bundle of bodies was spirally twisted. 

 This occurred in the appendage of a Hectocotylus which I found 

 in the ovarian capsule of a female Argonaut. In this one case I 

 saw a lively movement in the spermatozoa, the groups of which 

 formed regular progressive waves like the sea after a strong 

 breeze. 



What is there in the muscular tube which forms the axis of 

 the Hectocotylus ? is a most important question. 



Since we know that the Hectocotylus is developed as an arm, 

 it may be surmised, a priori, that the structure of the whole 

 axis will nearly resemble that of other arms, as indeed Kolliker 

 has already shown it does, so far as the muscular tube is con- 

 cerned. In fact, there lies in its interior a chain of ganglia, 

 which answer to the suckers. We see them best in longitudinal 

 sections which have been placed in solutions of chromic acid or 

 corrosive sublimate, and the single ganglia may be separated and 

 demonstrated as far as the root of the filiform appendage. From 

 this point the muscular tube may be very readily traced to the 

 extreme end, but it is difficult to make out what it contains : 

 certainly not the vas deferens ; for this, as Kolliker has shown, is 

 only attached superficially. In fresh specimens I saw a few times 

 a clear tube-like streak, which gave off lateral branches as well 

 in the axis of the sucker-bearing portion as in that of the 



