DesmidieceJ] infusokial animalcules. 237 



Confervfe ; and tlie fact of their containing amylum (starcli) is decisive 

 against the notion that they are eggs. 



"Although at first sight it seems to indicate the contrai-y, the 

 swanning of the zoospores or granules really affords a strong con- 

 firmation of the vegetable nature of the Desmidiece. The same 

 phenomenon is very generally observed in the Algae, but no similar 

 motion has ever been witnessed in the contents of an animal after 

 their cscajje. 



" The presence of starch, first observed by Meyen, seems now gene- 

 rally admitted. Mr. Dalrymple, who at first failed to detect it in 

 Closteria, afterwards did so in Penium Digitus : and Dr. Bailey, of 

 New York, has repeatedly proved its presence in Closterium Trahe- 

 cida, as weU as in other species. Mr. Ralfs has repeatedly noted 

 the efiiBcts of iodine on many of the Desmidiece ; but has found the 

 presence of starch indicated only when granules (the ova of Ehren- 

 berg) were present, as the fluid colouring matter always becomes 

 brownish. Precisely similar results followed the application of 

 iodine in Conjwjata in different stages of growth. In the young cell 

 there is no starch, but after its first appearance it contiaues to in- 

 crease, and is most plentiful in the sporangium. Of all the facts 

 which indicate the vegetable nature of the Desmidiece, the presence 

 of starch is tmdoubtedly the most important, since it is the most 

 easily subjected to the test of expeiiment. 



" The conjugation of the fi'onds in this family suppKes an equally 

 striking fact in proof that it belongs to the vegetable kingdom. 



" As in the Conjugata and other Algae, so in the Desmidiea, a bag or 

 cell forms between two individuals, the entire contents of which pass 

 out and unite together to form one reproductive body, which, be- 

 coming detached, leaves the parent corpuscles altogether empty. (See 

 P. 18. figs. 10 to 19.) Such an occiirrence is, I believe, not only un- 

 known amongst animals, but is contrary to aU our notions of 

 animal propagation. The Desmidiece, moreover, present the several 

 variations of form of sporangia, mot with in different genera of 

 Algae. 



" That the Desmidiea resist decomposition, exhale oxygen on ex- 

 posure to the sun, preserve the purity of water containing them, and, 

 when bui'ut, do not emit the peculiar odour so characteristic of 



