VESICULA PROSTATICA. 



1423 



is hindered from penetrating the vasa defe- 

 rentin. Jn order to this, the urine must, like 

 the semen in the previous view, enter into 

 the vesicle, which, distended by it, must by 

 its own pressure close the ejaculatory canals. 

 Hence the same difficulties recur as in the 

 first case. Since the urethra contains urine 

 only during the act of micturition, ;:nd is at 

 other times empty and collapsed, this fluid 

 must, even in its passage throng li the tube 

 by which it is discharged, pass into the vesi- 

 culu : a fact which is the less supposable, 

 inasmuch as to this end a backward move- 

 ment of the urine would be necessary. Be- 

 sides in many cases the situation of the 

 Weberian organ is such that, even if distended 

 by a fluid, it could not possibly operate in 

 such a way. And moreover, even where it 

 might perhaps be possible, it seems unneces- 

 sary, since the tumid or papillary margins 

 of the orifices of the vasa deferentia are suf- 

 ficiently closed by the passage of the urine 

 itself. 



One other conjecture of the physiologi- 

 cal value of the Weberian organ still remains 

 to us, viz. that it is a secretory appa- 

 ratus. It was found by the older anatomists 

 that here and there, for instance in the 

 horse, it was filled with a thick fluid, 

 mostly of a yellow tint. As was previously 

 remarked, this can only be secreted by the 

 coats of the Weberian organ. Morgagni 

 mentioned that the inner clothing of tiie onzan 

 was a mucous membrane, arid possessed a 

 glandular texture ; and the later researches 

 of Huschke and Lcydig have succeeded in 

 verifying a number of small glands therein. 

 These glandules have a different form in the 

 different animals ; for instance, in the rabbit 

 they are simply spherical ; in the boar they 

 are elongated tubes provided with buds and 

 processes. 



Whether such glandules always exist in the 

 Weberian organ must be verified by further 

 careful researches. Leydig could not find them 

 in the dolphin, nor could I in the dog. At 

 any rate they are absent where, as in the 

 deer, &c., the cavity has disappeared. 



Exteriorly to this mucous membrane, which 

 possesses a layer of cylindrical cells as an 

 epithelium, there is a layer of smooth mus- 

 cular fibres, which take the longitudinal di- 

 rection. In the hare only, in whom they 

 form a considerable layer, especially at the 

 lower end, they are more twisted together. 

 It is evident that this latter arrangement is 

 connected with the import of their Weberian 

 organ as a seminal vesicle. At all events 

 they are thus susceptible of more powerful 

 contractions, which one may produce in the 

 recently dead animal by galvanic and other 

 stimuli for a considerable time. Together 

 with these muscular fibres there is a quantity 

 of areolar tissue with white and yellow fibres. 

 Tiiis sometimes predominates, and where the 

 cavity disappears, it seems to occur alone. 



It can no longer be doubted that the 

 Weberian organ, at least where it is com- 

 pletely developed, and possesses an internal 



cavity and an opening, may prepare a secre- 

 tion ; but the nature and physiological import 

 of the secretion are as yet unknown to us. 

 H. Meckel* states, that he once found a 

 clear vitreous mass in the Weberian organ 

 of the rabbit, which from its re-actions was 

 gelatine. Nevertheless it is very improbable 

 that the secretion always consists of this sub- 

 stance, at least if I can judge from its external 

 physical properties. 



This secretion may easily be carried away 

 from time to time with the urine or the sperm. 

 Whether it plays any further part whether 

 it is possibly, like the secretion of the prostate, 

 subservient to the dilution of the semen (as 

 may be conjectured from the arrangement 

 of the Weberian organ in the hare) or to 

 other purposes, we know not. Alter all, 

 however, the function of the secretion can 

 scarcely be an important one. 



III. MORPHOLOGY. It is impossible that 

 we should be quite satisfied with what we 

 have learnt above concerning the physiological 

 value of the Weberian organ, (Granting that, 

 in some instances, it serves as a seminal re- 

 ceptacle, that in others it delivers up the pro- 

 duct of secretion, still its essential import is 

 certainly not thus exhausted. It seems that 

 the appl ; cation of the Weberian organ to 

 this or that end is but a casual result of its 

 general situation, rather than that it constitutes 

 a sufficient reason for its presence. We are 

 constrained to adopt such a view by the cir- 

 cumstance, that the Weberian organ is fre- 

 quently devoid of all connection with other 

 structures, and is even sometimes reduced to 

 a ligamentous thread, the functional value of 

 which one cannot imagine. 



Thus the Weberian organ takes a rank 

 amongst that class of structures which possess 

 not so much a prominent functional value, 

 as a morphological import ; which are neces- 

 sitated not so much by the actual require- 

 ments of life as by the general typical plan 

 of the structure. Should any one deny t!;e 

 existence of such a class of structures, it 

 would only be necessary to remind him of 

 the wing-stumps of many apterous insects, 

 of the bony girdle for the extremities of the 

 blind worm, of the embryonal teeth in the 

 bearded whale. All these are parts which 

 are of scarcely any physiological value to the 

 animals named, although under dillerent cir- 

 cumstances, and in other animals they fulfil 

 the most important functions : they are simply 

 morphological rudiments, which, according to 

 the common architectonic law, are repeated 

 even where they are useless. 



But such parts are found, not merely in 

 particular animals and groups, but also es- 

 pecially in the different sexes. Of what use 

 to the male individual are the milk-glands 

 and teats ? of what use to the female the well- 

 known rudimentary penis called the clitoris? 

 Are they not the plainest indications that the 

 male and female organs are constructed after 

 a common type, and that it is only by different 

 developments of the same elements that they 

 * Op. Cit. p. 49. 



