ANNELIDA TERRICOLA. 



ticular or ovarian masses been satisfactorily traced ; so that 

 Sir Everard Home was induced to believe that, in the kind of 

 intercourse above alluded to, there was no transmission of im- 

 pregnating fluid from one animal to the other, but that the 

 excitement produced by mutual contact caused both the ovaria 

 and testes to burst, so that the ova escaping into the cells of 

 the body became there mingled with the spermatic secretion, 

 and being thus fertilized, the ova were hatched internally, and 

 the young, having been retained for some time in the cells 

 between the intestine and the skin, were ultimately ejected 

 through apertures which were supposed to exist in the vicinity 

 of the tail. There is, however, little doubt that what Sir E. 

 Home conceived to be young earth-worms were in reality 

 parasitical Entozoa, and that in the mode of their propaga- 

 tion the animals under consideration exhibit but little devia- 

 tion from what is seen in the leech. 



Besides the ordinary mode of propagation by ova, it has 

 long been ascertained that some of the Annelida at least are 

 reproduced by spontaneous division. Bonnet, Miiller, and 

 Duges all agree that this is the case with certain species of 

 Nais ; and in Nais filiformis the process of separation has 

 been witnessed from its commencement to its termination. 

 The division was seen to occur near the middle of the body 

 of the animal, the posterior half remaining motionless upon 

 the mud of the bottom of the vessel, whilst the anterior por- 

 tion buried itself as usual ; after some days the truncated 

 extremity of the hinder part was observed to become swollen, 

 transparent, and vascular, and ultimately to assume the com- 

 plete structure of the mouth of the perfect animal ; it then 

 buried itself in the mud, and no doubt there completed its 

 development. 



CHEMICAL AND MEDICAL PROPERTIES AND USES. 



EARTH-WORMS may be used to diminish the vital tone or 

 cohesion of the solid tissues of the body, and thereby render 

 them more lax and flexible. They very effectually diminish 

 acrimony, and protect the sensible surface of the body from 

 the action of acid matter. The immediate advantage of these 

 medicinal agents has been stated by many to act merely me- 

 chanically, by lubricating and softening the parts to which 

 they are applied, or by sheathing them from the action of 



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