Miscellaneous. 505 



On the Seminal Fluid and Fecundation in the Arachnida. 

 By Emile Blanchard. 



The generative organs in the Araclinicia are formed upon a pecu- 

 liar plan, which is reproduced, with moderate modifications, in almost 

 all the types of that class of animals. 



The female organs are composed of membranous tubes presenting 

 vesicles or cells in their course ; the quantity of these cells is more or 

 less considerable, and in them the eggs are developed. These tubes, 

 usually two in number, terminating in a blind extremity, are generally 

 of great size ; this is the case in the Araneida and Tetracera (Ga- 

 leodes). In the Phalangia and Cheliferi they are united by their 

 posterior part so as to form a ring. In the Scorpionida thev have 

 a peculiar arrangement, so well known that I shall not dwell ujion it. 

 But in all cases they serve at once as oviducts and as reservoirs of the 

 seminal fluid. An observation of this nature, and various experi- 

 ments, enabled me to show that it was to the preservation of the 

 semen of the male in the ovarian passages, and not to a partheno- 

 genesis, as has been supposed, that we must attribute the niculty 

 indicated with regard to Spiders in captivity, of remaining fertile for 

 several years without copulating. The eggs are developed in the 

 vesicles or cells formed by the expansions of the ovarian ducts ; the 

 vesicles being constricted at their origin, the seminal fluid never 

 penetrates into them ; and it is only when the ova, being arrived at 

 maturity, have just passed into the oviduct, that they are impreg- 

 nated. In the vi\-iparous Arachnida, such as the Scorpions, in which 

 the embryos are developed within the ovarian cells, impregnation 

 nevertheless only takes place at a certain epoch, — namely when the 

 egg has become large enough to dilate the walls of the entrance of 

 its cell sufficiently to allow the passage of the fertilizing fluid. In 

 Phalangium and Chelifer the female apparatus is still more compli- 

 cated : there exists a true uterus, in which the eggs must remain for 

 a time before being expelled. 



The female apparatus of many Araneida, especially of those species 

 which live only one season, consists simply of the ovarian tubes 

 united near the orifice so as to form a short common oviduct ; but 

 in those Araneida whose existence is prolonged for several years, and 

 whose fecundity must persist after a single copulation (Segestrice, 

 Dysderce, &:c.), there is a special reservoir, a sort of copulatory sac 

 with fibrous walls opening outwards with the common oviduct, and 

 thus arranged to receive the liquid of the male directly during copu- 

 lation. 



In these Araneida, also, the seminal fluid presents a remarkable 

 character. Whilst in the Arachnida generally (in the Araneida, 

 Scorpionida, and Phalangiida) we see, swimming in this fluid, fili- 

 form spermatozoids and the little vesicles in which, as we know from 

 the observations of KoUiker, Wagner, and others, the spermatozoids 

 are formed, we find in the Segestrice, Di/sderce, &c., bodies of the 

 form of a flattened sphere, very regular, and so large that, when a 



Ann. <^- Mag. X. Hist. Ser. 3. Vol. v. 34 



