40 INTRODUCTION. 



from each other the long cells, which, applied end to end, and 

 more or less filled with green matter, occupy all its tubular 

 capacity." 



" In order to remove entirely the green matter, it was 

 necessary to open the cells which retained or held it, by 

 means of dissolvents. I contrived to effect this by squeezing 

 slightly together moistened ConfervcB, drying the mass, 

 afterwards submitting it to the action of lime, then alcohol, 

 ammonia, solutions of soda and potass diluted, removed 

 the azotized substances and green matter in solution. 

 Chlorine effaced the last traces by eliminating also a 

 brown substance ; hydrochloric acid, water, ether, and 

 alcohol perfected the purification by removing carbonate of 

 lime and fatty substances. The purified membranes of 

 Conferva rivularis and Oscillatoria presented then the com- 

 position of the other vegetable tissues." 



The nature of the contents of the cells of the Confervcs 

 is, it would appear by the preceding remarks, more complicated 

 than one would be led to suppose from a consideration of 

 the structure of the cells themselves. Starch is found in 

 them in considerable quantity, azotized substances, a fatty 

 matter, a colouring substance, and an odoriferous principle, 

 as well as salts. The Chara, M. Peyen remarks, contains 

 granules of starch, green azotized bodies, soluble azotized 

 substances, a fatty matter, a colouring substance, an 

 odoriferous principle, recalling the marshy odour of many 

 ConfervcBi chloride of potassium, carbonate of lime adherent 

 to the exterior of the membrane, and silica. 



Nitrogen, as is now Avell known, is the animalizing principle. 

 It is found, however, not as an organic constituent, but 

 merely as a product in small quantities throughout the 

 vegetable kingdom. It is especially noticed in the seeds of 

 the GraminecB, in the Fungi, and in the delicate reproductive 

 organs, in the pollen, &c. As a rule it has been remarked 

 that its presence is constant in the young parts and organs 

 of plants in which there is always a high degree of vitality, 

 in the establishment and maintenance of which this substance 

 would appear to be an essential element. M. Peyen, in the 



