288 Account of Professor Ehrenberg's 



opacity. In this manner he has demonstrated the existence 

 of one or more stomachs and an alimentary canal, with a mouth 

 and teeth, or masticating organs, of a wonderfully perfect de- 

 scription ; he has farther discovered in these animals, a system 

 of muscles, special organs of generation, and other structures 

 which he considers, not without probability, as constituting a 

 vascular and a nervous system. 



Professor Ehrenberg pointed out to me, when in Berlin in 

 1831, the anatomical structure of some of the infusoria, such as 

 he had made it out, more particularly that of the Hydatlna 

 senta. In that animal it is easy to perceive the different organs 

 which he has described and figured, and their characters are, 

 for the most part, so well marked as scarcely to admit of doubt 

 as to their nature. With regard, however, to those structures 

 which he considers as the vascular and nervous systems, more 

 especially the latter, it may be observed, that though his des- 

 criptions and drawings of these parts are very exact, his opi- 

 nion regarding their nature and functions, though not improba- 

 ble, must yet be allowed to be somewhat doubtful, and to stand 

 in need of further confirmation. 



The more recent researches of Dr Ehrenberg embrace seve- 

 ral different subjects of inquiry relative to the infusoria. 



l^^Of the Ditraiioji of Life and of the Development of the Infusoria. 



This part of Professor Ehrenberg's inquiries is of interest, 

 not only in relation to the natural history of the animals in ques- 

 tion, but also because the results he has obtained are, in his 

 opinion, calculated to correct the views entertained regarding the 

 constitution and production of organic bodies by those philoso^^^ 

 phers who have adopted the theories of spontaneous generatioii ^^^ 

 and of an indestructible living organized matter. While it i^^^^^ 

 universally admitted that all the more perfectly organized beings, 

 whether animals or vegetables, are propagated from parent 

 beings similar to themselves, the phenomena which attend the 

 production of some of the simplest tribes, led many physiolo- 

 gists to believe that they might take their rise from various ani- 

 mal and vegetable matters independently of pre-existing parents, 

 by a process which has been named spontaneous or equivocal; ^^^ 



