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AN ACCOUNT OF PROFESSOR EHRENBERG's MORE RECENT RE- 

 SEARCHES ON THE INFUSORIA. By WiLLIAM SHARPEYy 



M. Z)., Lecturer on Anatomy and Physiology. Communis 

 cated by the Author, With a Plate. 



In a former number of this Journal an able analysis was 

 given by Dr M. Gairdner of the discoveries which had been re- 

 cently made by Professor Ehrenberg of Berlin, respecting the 

 structure and economy of Infusory Animalcules, and of a new 

 method adopted by that naturalist for their systematic classifica- 

 tion. Since the period to which that paper refers, Professor 

 Ehrenberg has published the results of additional researches 

 made by him on the same subject, of which I purpose now to 

 give a short account. 



By referring to Dr Gairdner's paper, it will be seen that Pro- 

 fessor Ehrenberg"'s discoveries are calculated to bring about a 

 complete revolution in the views entertained by scientific men in 

 regard to the infusoria ; and they serve more especially to prove 

 that these animals have hitherto been assigned too low a place 

 in the scale of organized beings. Previously to his researches, 

 it was, with few exceptions, very generally believed, that the in- 

 fusoria were totally devoid of internal organs, that, in short, 

 they were little more than mere animated masses of gelatinous 

 matter ; they were supposed to be destitute of a stomach or in- 

 ternal alimentary cavity, the possession of which is regarded as 

 the most universal characteristic of animals; and though a mouth 

 or sucking orifice had been observed in some species, yet in the 

 greater number, the process of nutrition was believed to consist 

 simply in an imbibition of the surrounding fluid by the surface 

 of their bodies. Our imperfect acquaintance wilh the struc- 

 ture of these animals, has been due chiefly to their smallness, 

 and to the transparency and want of colour of their principal 

 internal organs. Dr Ehrenberg endeavoured to overcome the 

 difficulties thence arising, by the use of a microscope of a very 

 superior construction, and by the ingenious device of feeding 

 the animals with diff*erent colouring substances, which, when 

 swallowed, render apparent the stomachs or alimentary cavi- 

 ties previously hidden from view by their want of colour and 



