Bacillaria.] THE INFUSORIA. 181 



endowed with molecular motion, seen in the genus 

 Euastrum, are completely indentical with those observed 

 in Closterium and the conferva, and I see no good reason 

 why Closterium should not be placed near Euastrum. 

 The green corpuscles observed within the cells of most 

 of the Desmidiacea are similar to the green corpuscles 

 found in the cells of the conferva ; and though Ehrenberg 

 may consider them as ova, I have observed their develop- 

 ment into spores, and in several genera have distinctly 

 seen that they contained amylum, and sometimes that 

 they were even entirely composed of it. 



te The second section of the Bacillaria includes the true 

 Bacillaria, and are indicated by the term Naviculacea; 

 here are to be found those numerous forms, which, from 

 their occurrence in a fossil state, have lately given rise to 

 such a great degree of interest, and which Ehrenberg, and 

 many other naturalists, regard as undoubtedly belonging to 

 the animal kingdom. 



" The reasons adduced for such belief, however, are so 

 weak, that the conclusions deduced from them are yet, for 

 the most part,^very doubtful. 



" The movement of the Bacillaria, however free it may 

 be, is by no means so free and active as that of the spores 

 of the Algae and the spermatic animalcules, which are 

 plants, or at least parts of plants, and the motion is no 

 very positive ground for the belief of their animal condition. 

 The common mode of propagation seen in Bacillaria is 

 that of self- division, which is also proper to the cells of 

 the higher plants ; the increase by spores or ova ensues 

 but rarely. The form, structure, and especially the 

 habitus of the Bacillaria are evidently of that kind to lead 



