On Parasitic Animals. 



101 



on this subject, which he has published in the Annales de Phy- 

 sique et de Chimie, Sept. 1828, that we extract the table which 

 contains the analyses of the ashes of some species of the genus 

 Equisetum. The great quantity of silica which these ashes ap- 

 pear to contain, and which exceeds the half of their weight, is a 

 remarkable fact, when we consider it in its relations, whether to 

 the mechanical properties of the equiseta, or to the optical pro- 

 perties possessed by the small crystals with which their surface 

 is sometimes covered. The presence of silica in such large pro- 

 portion is also in accordance with the observation of M. Bracon- 

 net, that the equisetaceae grow only in very siliceous soils, almost 

 entirely destitute of carbonate of lime. But how is this great 

 quantity of silica itself dissolved, in order to be introduced into 

 the tissue of the plant ? This is one of the subjects which has 

 especially occupied the attention of the author. To form a cor- 

 rect idea of this particular point of inquiry, it is necessary to 

 read the memoir itself We shall here only remark, that potash 

 does not contribute, as might be expected, to produce this solu- 

 tion, for the ashes of these vegetables present the curious, and 

 perhaps unique, fact, of not possessing alkaline properties, or 

 only in a feeble degree in some cases. 



Composition of the Ashes. 



On Parasitic Animals, and on a new Genus of that Family. 



xtLmongst the intestinal worms or parasitic animals, there are 

 some which have at the lower surface, or al the posterior ex- 

 tremity of the body, one or more cup-shaped organs, more or 



