3l8 BUI.LETIN OP THE BUREAU OF FISHERIES. 



having oriented itself on the surface of the egg exploded and penetrated the chorion ; 

 this happened in three different species of crabs. The capsule of the normally oriented 

 sperm exploded while in view, and the nucleus was drawn into the egg, but it was impos- 

 sible to distinguish anything whatever within the opaque ovum. He inferred, but did 

 not prove, that this series of events represented a true fertilization process. 



Several attempts were made at artificial fertilization of lobster eggs at Woods Hole 

 in 1 89 1, but like the experiences of Koltzoff in 1906 they were unsuccessful. There are 

 the difficulties of first obtaining perfectly ripe eggs, and, secondly, of meeting the other 

 conditions of fertilization in which the secretion of glands from the ovaries, oviducts, 

 or integument of the swimmerets may play a part. I made glycerine extracts from 

 the ovaries and oviducts in the hope of finding a chemical stimulus for the sperm, but 

 did not succeed, the primary difficulty of getting the organs in the proper state of matur- 

 ity being at that time insurmountable. It was impossible, also, to get any secretions 

 from the swimmerets by applying electrical stimulation to the ventral nerve chain, 

 from which they are innervated. 



THE SEMINAL RECEPTACLE, COPULATION, AND IMPREGNATION. 



The habits of the lobsters at the time of sexual union, so far as at present known, 

 have been already described. (See p. 302). We have now to consider how the female is 

 actually impregnated, that is, how the spermatophores are transferred by the male to 

 her receptacle. According to the account quoted above the transfer is quickly made 

 while the female Ues on her back, and in the three or four cases observed when her shell 

 is soft. 



While no direct observations on the further course of events are as yet available, 

 the structure of the spermatophore, the male stylets, and the female receptacle render 

 plausible at least the following account, which is purely conjectural. Before proceeding 

 with this, however, it will be necessary to examine the secondary sexual structures with 

 greater care. The seminal receptacle (fig. 6, pi. xliii) Ues on the underside of the female 

 immediately behind the opening of the oviducts and between the bases of the last two 

 thoracic legs. (Compare p. 301.) It presents the appearance of a light blue shield with 

 deep median groove. When examined closely it is found to consist of a pair of wing- 

 like processes, the enlarged sterna of the seventh thoracic somite, with a middle piece 

 belonging to the succeeding segment wedged between their posterior extremities. The 

 lips of the median groove are elastic, and if forcibly depressed are seen to open into 

 a membranous pouch, in which the spermatozoa are carried. The pouch is laterally 

 compressed and extends directly upward at right angles to the long axis of the body and 

 is supported on the link-work of the internal skeleton. (Fig. 4, pi. xxni, sac.) We 

 should notice that this sac, far from being a delicate structure, is well adapted to receive 

 rough treatment with impunity. Within, the middle wedge-shaped piece is continuous 

 with a pair of calcareous rods which form a solid frame for the posterior and upper 

 part (or bottom) of the sac, where they are firmly sutured to the endophragmal skele- 

 ton. Within the pouch this sternal bar is prolonged into a stout keel, where it is 



