222 MESSRS. HANCOCK AND EMBLETON ON THE ANATOMY OF DORIS. 
be the case in Doris. We have failed to find the double sacculi and the inclusion of 
the vas deferens in the oviduct, at the same time we acknowledge that it is matter of 
great difficulty to determine the exact functions of the several parts of the apparatus. 
But however the matter may be in the above Mollusks, as regards Doris we are 
still inclined to adhere to our own opinion founded on observation, namely, that the 
disputed organ attached to the liver is simply an ovarium ; that there is no duct in- 
cluded in the oviduct, but that it is a simple tube, the function of the dilated portion 
of which is not merely to give passage to the ova, but to serve as a sort of reservoir 
for the seminal fluid, which is allowed to pass from the spermatheca along it, even 
as far as the ova in the ovarium. The testis and vas deferens, it will be seen, we 
recognize in that tube, of whatever length and however convoluted, which extends 
from the oviduct to the penis. 
The position and arrangement of this testicular tube and its connection would 
seem of themselves to warrant this recognition; but when we find an almost micro- 
scopically convoluted tubular gland, almost the type of the mammalian testis, super- 
added, as in D. tuherculata, Veranv, and occupying part of the position of the larger 
or loosely convoluted tube of the true D. tuherculata, and that in some species, as in 
D. repanda, D. verrucosa and D. coccinea, there is a lengthened duct that may very 
aptly be compared to a vas deferens, leading as it does from the fusiform glaud to 
the penis, then we must look upon our conclusions as in some degree warranted. It 
is true that this convoluted tubular testis joins the oviduct ; but in this circumstance, 
instead of seeing anything that militates against our theory, we find a certain degree 
of confirmation of our views of the condition of hermaphroditism in which these 
creatures are placed. The connection with the oviduct we suppose is to provide the 
means of self-impregnation, when the extremely solitary habits of some of these mol- 
lusks render such necessary ; and lastly, the evidence to be elicited from the contents 
of the testis and other genitalia would seem further to support what we have here 
advanced. 
In D. tuherculata of our coasts, the testis, examined immediately after coitus, con- 
tains granular tenacious mucus, having imbedded in it numerous large granular 
vesicles, each having one or more clear cells developed in its interior. These 
vesicles* appear to be spermatophora in an early stage of development. In the fusi- 
form mass, making part of the testis in D. tuherculata, Vekany, the same kind of 
bodies has been observed. The same specimen of D. tuherculata of our coasts, the 
contents of whose testis have been just noticed, was examined as to its spermatheca; 
this was found to contain multitudes of minute elliptical cells, apparently enclosed 
in delicate fusiform membranous sacs, together with a few scattered spermatozoa. 
These sacs are the developed spermatophora -f-, and enclose cells, — spermatozoa in an 
incipient state. The spermatheca of other specimens taken during the breeding 
season, we found to be filled with large fusiform sacs, containing either simple cells, 
* Plate XV. fig. 6. f Plate fig. 7. 
