SANGUISUGA. 



truded, 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. Append- 

 ed to the bottom of this organ is a convoluted canal, which 

 communicates with two round whitish bodies ; these are the 

 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 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 are subjected to its vivifying influ- 

 ence ; 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 com- 

 plete 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 interior of this viscus. But all these suppositions are easily 

 reconcilable with each other ; there is no doubt that the semi- 

 nal liquor is^deposited in this reservoir during the copulation 

 of two individuals ; neither would any one dispute that the 

 ova are collected in the same cavity before they are expelled 

 from the body. As to the discussion whether the young are 

 born alive or not, or, as it is generally expressed, whether 

 leeches are oviparous or viviparous, it is in this case merely a 

 question of words ; for in a physiological point of view, it can 

 make not the slightest difference whether the ova are expelled 

 as such, or whether, owing to their being retained by acci- 

 dental circumstances until they are hatched internally, the 

 young leeches make their appearance in a living state. 



The increasing scarcity of leeches renders their preservation 

 and propagation objects of primary importance. The death 

 of a vast number of leeches is occasioned by errors in the 

 method of keeping them. Though aquatic animals, it is not 

 enough that they be supplied with water. They breathe by 

 their entire surface, and are accustomed to change their skins 

 every four or five days. Their body is covered, like that of 

 all animals and plants which inhabit the water, by a shiny or 

 mucilaginous fluid, which not only enables them to glide 



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