252 REPORT— 1851. 



to describe in minute detail the specific varieties under which these organs 

 occur in the class. Leading generic types will however be described, which 

 will serve to convey to the mind a clear conception of the structural laws 

 according to which this system of organs is constructed. 



Those of the Leech, Lumbricus, Nats, Arenicola, Terebella and Albione, 

 will conduct the physiologist far towards a full and complete conception of 

 the ultimate anatomy and relations of the reproductive organs in all other 

 Annelida. Each description will be preceded by a summary of what has 

 been up to the present date taught by the best systematic authors with re- 

 ference to these organs. The succeeding account is transferred from the 

 work of Mr. Rymer Jones, the best digest of comparative anatomy at pre- 

 sent known. "In the Leech, the glands which furnish the masculine fluid 

 are about eighteen in number, arranged in pairs upon the floor of the visceral 

 cavity. Along the external edge of each series there runs a common canal, 

 or vas deferens, which receives the secretion furnished by all the testicular 

 masses, placed upon the same side of the median line, and conveys it to a 

 receptacle whence it accumulates. The two reservoirs, or vesiculce seminales, 

 if we may so call them, communicate with a muscular bulb situated at the 

 root of the male organ. This organ is frequently found protruded from the 

 body after death; it is a slender tubular filament which communicates by its 

 origin with a contractile bulb, and when retracted, is lodged in a muscular 

 sheath. The male apparatus is thus complete. The fecundating secretion 

 derived from the double row of testes is collected by the two t^asa deferentia 

 and lodged in two globular receptacles situated on either side of the bulb ; 

 it is thence conveyed into the muscular cavity which is placed at the root of 

 the male organ of excitement, through which it is ultimately ejected.*" 



The foregoing description, quoted from the work of Mr. Rymer Jones, is 

 founded upon the original dissections of M. Duges; it relates exclusively to 

 the male apparatus, and to its general accuracy the author can testify from 

 the results of his own dissections. The passage which now follows purports 

 to be descriptive of the correlative feminine system of the Leech, and is 

 taken from the same excellent work. To it special attention is invited. " The 

 ovigerous or female organs of the Leech are more simple in their structure 

 than those which constitute the male system ; they open externally by a small 

 orifice situated immediately behind the aperture ; the penis is protruded, the 

 two openings being separated by the intervention of about five of the ventral 

 rings of the body. The vulva or external canal, leads into a pear-shaped 

 membranous bag, which is usually, but improperly, named the uterus. Ap- 

 pended to the bottom of this organ is a convoluted canal which communicates 

 with two round whitish bodies ; these are ovaria. The germs, therefore, 

 which are formed in the ovarian corpuscles, escape through the tortuous 

 duct into the uterus, where they are detained for some time prior to their 

 ultimate expulsion from the body. The exact nature of the uterine sacculus, 

 as it is called, is imperfectly understood ; some regard it as a mere receptacle 

 wherein the seminal fluid of the male is received and retained until the ova 

 come in contact with it as they pass out of the body, and thus subjected to 

 its vivifying influence ; other physiologists believe that the germs escape 

 from the ovaria in a very immature condition, and suppose that during their 

 sojourn in this cavity they attain to more complete development before they 

 are ripe for exclusion; while some writers go so far as to assert that leeches 

 are strictly viviparous, inasmuch as living young have been detected in the in- 

 terior of this viscus ; but all these suppositions are easily reconcileable with 

 each other : there is no doubt the seminal liquor is deposited in this reservoir 

 * Animal Kingdom, by Rymer Jones, p. 200. 



