1 6 niBLIOGRAPHY. 



Bonnet, Goezc, Gleichcn, Eichorn, Spallanzani, and Schranck, towards the 

 termination of the eighteenth, and Treviranus, Oken, Dutrochet, Nitzsch, 

 and Bory de St. Vincent, during the commencement of the present century, 

 are among the more conspicuous of these. Gleichen's name, perhaps, 

 deserves special notice, he being the first to demonstrate, through the admix- 

 ture of finely comminuted carmine with the water, the capacity of Infusoria 

 to appropriate this and other solid substances as food. Spallanzani detected 

 within the body-plasma of various species the bubble-like pulsating space or 

 spaces afterwards denominated contractile vesicles, while the presence of an 

 internal, more solid, gland-like structure, the nucleus or endoplast, and the 

 capacity of many to increase by longitudinal or transverse subdivision were 

 familiar to the majority of these observers. Examples of these last-named 

 phenomena were, indeed, figured and described by Miiller, and had, as already 

 intimated, been observed long previously by Trembley in association with the 

 Stentors or trumpet-animalcules. Dutrochet, in the year 1812, achieved a 

 progressive step by the recognition of the essential distinction of all the 

 species referred by O. F. Miiller to the genus Brachionus ; these were 

 shown to exhibit a much higher organization than the ordinary Infusoria, 

 possessing well-developed internal organs, and a much more complex type 

 of external contour, and were now distinguished for the first time by the 

 title of Rotiferae or wheel-animalcules. This distinction, pointed out by 

 Dutrochet, was recognized by Lamarck and Cuvier in their respective 

 classifications of the animal kingdom, the Infusoria as embodied in Cuvicr's 

 scheme including all of Miiller's types, subdivided into two leading orders, 

 the one including the more complex Rotiferae, and the other the appa- 

 rently structureless and homogeneous animalcules. These latter were, 

 indeed, accepted by Cuvier and all leading authorities up to the year 1830 

 as the simplest forms of animal life, exhibiting a degree of organization 

 most appropriately compared with mere specks of animate jelly variously 

 modified in external shape. 



With the last-named date commenced an entirely new era in the his- 

 tory of the Infusoria. For fourteen years previously Christian Gottfried 

 Ehrenberg had been devoting studious attention to the investigation of 

 the lowest grades of vegetable and animal life, the matured fruits of 

 which now took the scientific world completely by surprise. He at this 

 time commenced the publication of his various essays, seeking to demon- 

 strate that the Infusoria, notwithstanding their minute size, possessed a 

 degree of organization as perfect and complex as that of the higher 

 animals, which culminated in the year 1838 in the production of his 

 world-famed history of the Infusoria, ' Die Infusionsthicrchen als Volkom- 

 mene Organismen.' This magnificent folio treatise, embodying no less 

 than 532 pages of letterpress and an accompanying atlas of 64 coloured 

 plates, including several hundred specific forms delineated for the most 

 part with a life-like exactitude, will ever remain a lasting memorial of the 

 unflagging industry and talent of this most indefatigable investigator. 



