8 2 ON THE APPENDICES GENITALES iCLASPERSl IN THE SELACHIANS. 



the semen, preventing it from flowing off in the water. Then the part played by the secretion, would 

 not be restricted to facilitating the introduction of the appendix - - which part I regard as quite in- 

 contestable — , and to protect the different parts partaking in the copulation (eventually also the outer 

 skin) against a severe friction; but the secretion would also be of direct importance for the impreg- 

 nation by yielding a means, as it were, of keeping together the semen and leading it along the 

 appendix into the oviduct. 



It must be possible to some degree to test this supposition by examining the way in which 

 the spermatozoids act in relation to the fresh secretion; but unfortunately I have had no oppor- 

 tunitv for that 1 ]. For the present I must leave the value of this and my other suppositions to the 

 testing of others, and own that I have only been able to advance the understanding of the func- 

 tions of the ventral appendages very little; most of the epiestions raised by the different, rather com- 

 plicated structures, especially in the terminal part, must still be left quite unanswered, as also such 

 facts as the large extent of the glandular bag in most Sharks must still appear mysterious 2 ). With 

 regard to some of these questions it may be dubious, whether they ever will be solved; but with 

 regard to others, especially the question of the appendages as means of the conveying of the semen, 

 it would seem that they might be solved by observations. It is to be hoped that the future will 

 bring such observations. 



Addenda. 



I have been unwilling in this translation to make any essential alterations of the original 

 Danish text. This latter was ready printed in August 1898. I regret to say that shortly after I 

 saw that I had quite overlooked a short, but rather essential contribution by A. Schneider to the 

 question of the function of these organs; it is only little more than half a page, and is printed in 

 Zool. Beitrage vol.1, 1885, p. 61 3). In this contribution he says of the glandular bag: Dieser Sack 

 hat jedoch noch eine andere bisher gauz ubersehene Function. Er ist em Receptaculum seminis, Ich 

 habe bei Sfiinax Acanthias Samen dariu gefunden. Die Begattung diirfte deshalb bei den Plagiostomcn 

 in der Weise stattfinden, dass zuerst das Receptaculum seminis mit Samen gefiillt wird uud von da 

 aus mit Hixlfe des in den Uterus eingefuhrten Pterygopodium die Immissio seminis stattfindet. Bei 



') Hitherto only very little is known of the chemical relations of this secretion. Davy (I.e. 1839, p. 145) says it is 

 neither acid nor alkaline, and that it has a very indistinctly acrid after taste. Moreau, on the contrary, declares it to be 

 acid (I.e. p. 258); this, however, can scarcely be correct, as in this case it would have a bad influence on the spermatozoids 

 with which it will scarcely avoid to come into contact. 



2 1 For those, who are of opinion that Agassiz has solved the question of the function of the appendages correctly, 

 these bags, perhaps, will not appear quite so mysterious; Gar in a 11, for inst. says (Proc. BosL Soc. 1874, p. 173): That the 

 cavity upon the ventrals, containing the muscular gland, fills so readily with the sperm when the claspers are erected, and 

 that its contents are expelled, upon contraction of the muscles around it, with such certainty to their ends, when restored to 

 their normal position, are evidences that it acts as a forcing or squirting apparatus . I must, however, object against this 

 1 1 that I cannot see that the sperm upon the whole can he filled into the bag, still less, that it can be done easily; and 

 2) that spermatozoids never have been found in the glandular bag, although its contents have several times been subjected 

 to microscopical examination, also with the object of seeking spermatozoids in them. 



3) As it is reported in < Biol. Centralbl. vol. Ill, 1SS3, 110.7, P-224, this contribution to the Beitrage» must have 

 appeared two years before the completing of the said volume. 



