SECRETION. 105 



the peculiar narcotic smell of the plant from which they 

 may have been taken. The great quantity of carbon 

 and the presence of nitrogen, distinguish them amongst 

 other characters from the substances already mentioned. 

 Many of the plants, entering into our Materia Medica, 

 possess an alkaloid, and it is in general upon this that 

 their activity and power depend : in some as many as 

 four or five have been supposed to have been found. 

 The best known amongst them are 



!* ) 



::::::::::::.:::::::: 



tine, etc., etc., etc ) 



Morphia 



Codeia* " j- In the Papaver somniferum. 



Narcotine, 



Bruc'a * " \ ^trychnos mix vomica. 



Atropia Deadly Nightshade. 



Hyoscyama Henbane. 



Veratria Meadow Saffron. 



Conia Hemlock. 



Emetina Ipecacuhana. 



Picrotoxia Cocculus indicus. 



Daturia Thorn Apple. 



Quinia Yellow Peruvian Bark. 



Digitalia, Solania, etc., etc., etc. 



131. Under the head of Extractive Matter, a great 

 number of substances are included, which form residues 

 in analytical operations upon more compound vegetable 

 products, but no general idea can well be given of them. 



132. There are certain inorganic substances found 

 within the cells of plants, composed chiefly of oxalate 

 and phosphate of lime, and occuring in the shape of aci- 

 cular crystals, either distinct from each other, or united 

 into a compact fibrous bundle ; and again, as Mr. Que- 

 kett expresses it, as small bodies composed of many 

 crystals, which radiate from the same centre, thereby 

 forming a more or less spherical mass : according to this 

 gentleman the four-sided prism is most probably then- 

 ultimate figure. 



133. These bodies are called Raphides, and occur in 

 members of all divisions of the vegetable kingdom; 



