jo5 French Nalio?ial Insliiute. 



He makes a reflection on thi? subject, the truth of whicii 

 is denionitrated by every animal organization with which 

 we arc acquainted. 



" Nature," he sayi, " is ever fertile in her resources : 

 she never i)asses to a secondary combination until her pri- 

 mitive tvpe and its modilications become insufficient, and 

 never adds an organ until new circumstances require greater 

 efforts and more powerful means." 



It is this principle which forms the basis of coni|>arative 

 anatomy : it is this principle which has given birth, not 

 only to the branch of this science which compares with 

 each other the different species, but also to another more 

 novel and not less curious branch, which compares with 

 each oiher the different organs of one and the same species. 

 Vicq-d'Azyr had already given an example of this second 

 branch in liis Meiuoire sur les Rapports des JMemhes an- 

 terleurs ct poster'iciirs. M. Dumeril on the present occa- 

 sion has given another example, which nmy be regarded as 

 following up the former. 



M. Villars, correspondent of the class at Strasburgh, has 

 presented two memoirs on the structure of the nerves. He 

 liiinks he has discovered, by the help of the microscope, 

 that the envelop of the nerve is itself composed o-f nervous 

 fibres : but our committee has not yet been convinced of 

 the truth of this assertion from ocular demonstration. 



Veiietable anatomy has for several years been much in- 

 debted to M. Mirbel : — the Royal Society of Gotlingen 

 made this the subject of an annual prize, which occasioned 

 the publication of several dissertations, the chief of which 

 were those of Messrs. Link, Treviranus, and Rudolphi, 

 all of them professors in dift'ercnt German universities. These 

 learned naturalists agree in the conclusions of M. Mirbel, 

 adding some observations to his, but contradict him on 

 sorne points. This opposition induced him to publish in 

 his turn a defence of his theory, in which he determines 

 it with more precision l)v nciueing it into aphorisms, and 

 in wliich he endeavours to show tliat the most of the ob- 

 jections made against him, either proceeded from his mean- 

 hig being misunderstood, or from his observations having 

 been repeated with too little care. 



The same botanist lias this year presented to the class a 

 particular memoir on the germination of the grasses, and 

 another on the distinguishing chara':tcrs of the mouoeolyle- 

 doutal and dicotyledontar plants. 



In the former he has shown that the stigmata of wheat 

 \inite in a small channel which proceeds towards the base 



of 



