278 Bibliographical Notices. 



the novelties in the Cryptogamic flora of France was justly admired, 

 and he soon became known as the great medium of correspondence at 

 Paris on every subject connected with that branch of botany to which 

 he had determined to consecrate his labours. Materials rapidly in- 

 creased upon his hands, the consequence of which was, that month 

 after month there was a constant flow of new and interesting intel- 

 ligence from his pen. This, from the very nature of the case, is 

 scattered up and down through a multitude of works of various de- 

 scriptions, many of them exceedingly voluminous and costly, and they 

 are therefore inaccessible to a great portion of those who wish to 

 consult them. By the advice of Professor Fries, he has therefore 

 determined to collect diagnoses of all the new species which he has pub- 

 lished, and they ai'e now united in a handsome volume, accompanied 

 by copious indices, and enriched here and there with interesting notes. 



The following extract relative to the motion of DiatomacecB is an 

 example of the sort of matter with which the technical characters are 

 here and there interspersed. In describing a new species of Navicula, 

 which forms a part of the organic matter which occurs in the waters of 

 Vichy, he takes occasion to give an extract from a letter of M. Petit : — 



" The motion of these Naviadce is well worth attention. It is 

 more or less decided according to the degree of their development. 

 In their more or less rapid progress across the field of view, they 

 appear to have a certain degree of consciousness, so as to avoid any 

 obstacles with which they meet. They advance for the purpose of 

 investigation ; they try them with one of their extremities ; but they 

 appear to do this with a certain degree of precaution. It seems as 

 though they smell at these obstacles, that they examine them, and 

 try means of avoiding them. 



" I may add, in reply to one of your observations, that I am quite 

 certain that the movements of these little creatures do not depend on 

 currents arising from the evaporation of the fluid on the stage, or 

 from any other physical cause, of which it is easy, with a little atten- 

 tion, to con\'iuce oneself. These movements are certainly self-depend- 

 ent ; for the creatures wander in different, and frequently opposite 

 directions ; and they consist not simply in an agitation without 

 object, but seem to be directed by a sort of instinct. On carefully 

 watching them, we see them turn round obstacles, when they cannot 

 pass above or below them. Sometimes, when they are entangled in 

 a mass of dead organic matter, they put it in motion by their struggles 

 to extricate themselves. You may therefore consider as certain all 

 that I tell you about the spontaneous motions of our Naviada, which 

 I scarcely regard as a vegetable. 



" This morning I have sho'Rii the motions of the Uhthrix and 

 Navicula to Dr. Seguin, who is used to the microscope, and was much 

 struck with them. He has verified all the information which I have 

 sent you. 



" I said in my first letter, that we meet sometimes with large 

 quantities of little Navicidce not yet, as it appears to me, completely 

 developed, and which have not at that time the lanceolate extremities. 

 In this state or stage of growth they possess no motion, which they 

 acquire in proportion as they increase in size, and do not possess 



