VEGETABLE FIBRINE. 45 



From what substances, it may be asked, is the 

 blood formed, by means of which their organs are 

 developed ? This question may be answered with 

 certainty. 



Chemical researches have shewn, that all such 

 parts of vegetables as can afford nutriment to ani- 

 mals contain certain constituents which are rich in 

 nitrogen ; and the most ordinary experience proves 

 that animals require for their support and nutrition 

 less of these parts of plants in proportion as they 

 abound in the nitrogenised constituents. Animals 

 cannot be fed on matters destitute of these nitro- 

 genised constituents. 



These important products of vegetation are espe- 

 cially abundant in the seeds of the different kinds 

 of grain, and of pease, beans, and lentils ; in the 

 roots and the juices of what are commonly called 

 vegetables. They exist, however, in all plants, 

 without exception, and in every part of plants in 

 larger or smaller quantity. 



These nitrogenised forms of nutriment in the 

 vegetable kingdom may be reduced to three sub- 

 stances, which are easily distinguished by their ex- 

 ternal characters. Two of them are soluble in 

 water, the third is insoluble. 



When the newly-expressed juices of vegetables 

 are allowed to stand, a separation takes place in a 

 few minutes. A gelatinous precipitate, commonly 

 of a green tinge, is deposited, and this, when acted 

 on by liquids which remove the colouring matter, 



