PASTEURj ON NUTRITION OF THE MUCEDINEiE. 215 



perhaps, of still greater importance to remark — these results 

 iDdicate a method by means of which vegetable physiology- 

 will be enabled to attack, without difficulty, the most difficult 

 questions respecting the life of these little plants, so as to 

 lead the way surely to the study of the same problems in the 

 higher plants. 



Even should it be feared that it may not be possible to 

 apply to the larger plants the results afforded by organisms 

 apparently so low, still great interest will equally attach to 

 the resolution of the difficulties which arise in the study of 

 vegetable life, when we commence with those plants whose 

 less complex organization renders our conclusions easier and 

 more certain. In their case, the plant is reduced in some 

 measure to the condition of a cell ; and the progress of science 

 shows more and more that the study of the most complicated 

 actions performed under the influence of either vegetable or 

 animal life is reduced, in its ultimate analysis, to the discovery 

 of the phenomena proper to the cell. 



water affords nitrates and ammoniacal salts containing assimilable azote, toge- 

 ther with salts of potass, soda, and lime, all favorable to vegetation ; but 

 another element, equally indispensable, was always found to be wanting — 

 phosphoric acid, which, in spite of numerous researches, had not been dis- 

 covered in rain-water. M. Boussingault states tliat this lacuna in the 

 fertilizing elements of rain has just been supplied by M. Burral, who has 

 recently ascertained the existence of phosphates in rain-water. 



