THE ANATOMY OF THE LEECH. 31 



nates in a convoluted ccecal tubulus. Between this median organ and the great 

 bilateral series of ovario-uterine organs there is no communication whatever. If, 

 therefore, during the union of two individuals a fluid is emitted by the male organ 

 into the interior of the sacculus, it requires no further argument to shew that it can 

 proceed no further, that it can reach no other part of the reproductive system. In 

 congress therefore these two parts can subserve no other than the purposes of 

 first: mechanically uniting the individuals, and secondly: of stimulating the 

 sexual organs. During those periods when the fertilizing fluid is not required for 

 the office of fecundation, it is probably discharged externally as a superfluous excre- 

 tion in part through the intromittent organ. According to this explanation, to the 

 larger testicular bodies should be assigned the mechanical uses only of seminal 

 receptacles, compressing what they may contain, either backwards into the ovario- 

 uterine organs, or forwards to be expelled through the penis as an excretion. The 

 penis therefore is the only means common to the whole male system by which it 

 communicates with the exterior, the so-called "respiratory saccu'i," being the 

 means by which each testis separately communicates with the exterior. 



It is with considerable diffidence that I express a doubt as to the 

 correctness of Dr. Williams' observations on two points, and as my 

 dissections induce me to do so, I will now briefly refer to the annexed 

 diagram, Plate 1, Fig. 1, to illustrate what I believe to be the true 

 history of the organs which are respectively called ovipero-uterine 

 sacs and testes. 



The following references to figure 1, on the plate, will enable tbe 



reader to apply the observations offered here to the results which 



dissection exhibits with the aid of the microscope: 



(«) Ovaries, (b) Testes, (c) Vesicula Seminalis. (d) Common duct- 



(e) Intromittent organ and lull, (f) Uterus (?) or pouch. 



(_</) Termination of common duct in lulb. 



Except by Dr. "Williams, hitherto no chain of connexion has been 

 described between the so-called testes ; they are in all the drawings 

 shown as attached to the duct common to each so-called testis 

 and sac. In my dissection made from the dorsal region, I find 

 that a delicate vessel passes, as represented in the annexed plate, 

 between each gland, forming an intimate communication between 

 them. All these glands terminate in a common duct at the base of the 

 intromittent organ. 



Dr. "Williams and others have described the base of this last-named 

 instrument as possessing also a gland-structure, but no such structure 

 exists; on the contrary the bulbous expansion evidently possesses 

 contractile walls and presents no glandular appearance. 



The so-called uterus is, as Dr. Williams states, a sacculus, termi- 

 nating in a cul de sac, and I can find no trace of connection between 

 it and the other bodies. In shape it is somewhat like the human 

 stomach, and on its lesser curvature enfolds a glandular mass. 



