72 MULLER ON THE MALE OF 



If then the abdominal capsule of Hectocotylus Tremoctopodis 

 is analogous with this lobe, and perhaps also with the terminal 

 vesicle of Hectocotylus Octopodis, we must give up its supposed 

 analogy with the pigmented capsule of the two other Hecto- 

 cotyli; and the Hectocotylus Tremoctopodis seems to possess 

 nothing comparable therewith. 



On the other hand, the presence of a free penis by no means 

 constitutes an absolute difference from the other Hectocotyli. It 

 is its position chiefly which distinguishes it from the appendage 

 of Hectocotylus Argonautae, and the circumstance that the ductus 

 deferens lies in its interior, whilst in the latter it is only attached 

 externally to the prolongation of the axis. If it were certain 

 that the filament which we find in the terminal vesicle of Hecto- 

 cotylus Octopodis had the same signification, and is not a mere 

 seminal tube, the analogy of the three Hectocotyli in this point 

 would be complete. 



In the other portions of the sexual apparatus, the testis and 

 the ductus deferens, such an agreement cannot at present be 

 demonstrated. 



Kolliker has named ( testis ' a vesicle which generally com- 

 pletely fills the abdominal capsule. The cleft outer capsule 

 readily separates again into two layers, the outer of which is 

 similar to the general cutaneous investment: under the epithe- 

 lium there is a fibrous network with numerous vessels, whose 

 capillary loops may be seen in the delicate terminal prolonga- 

 tion. The second layer consists, like the subcutaneous tissue of 

 the back, of muscular bundles, which especially affect a longi- 

 tudinal arrangement. Upon the inner surface it supports a layer 

 of delicate polygonal cells. Below this again comes the so-called 

 sac of the testis, which may be easily separated. Its wall has a 

 peculiar checkered (carrirtes) appearance ; t\vo layers of fibres 

 are visible, which cover one another very regularly like the 

 fibres of a tissue, at right angles, or often at somewhat oblique 

 angles. The fibres are when isolated somewhat rigid, but often- 

 times not dissimilar to muscular fibres. Elsewhere, however, 

 they can be hardly separated at all, and in many places almost 

 structureless layers occur. 



In the interior of this vesicle there was always contained the 

 thread described by Kolliker, which consists almost entirely 



