03 



d'histoirc naturelle, art. Arthrodiees) and Mr. Nitzsch 

 (Beitrage zur Infusorienkunde. Halle, 1817) threw 

 later some light on their nature. The first placed 

 them between the two organic kingdoms , and the 

 second acknowledged their animality. After them, the 

 celebrated traveller in Africa and Asia, Mr. Ehren- 

 berg, author of important discoveries, ranged the 

 animalcules , of which we are treating , among the 

 cuirassed Infusoria with feet alternately moving in 

 and out ; and about the same time several naturalists, 

 endowed with less perseverance and sagacity, and 

 without recurring to analogy nor to anatomy, placed 

 them in the vegetable kingdom. Professor Agardh, 

 of Lund in Sweden , formed with them a family of 

 plants, which he called Diatomeae , and ranged them 

 in the lowest cathegory of the Algs. He was follo- 

 wed by MM. Lyngbye, Turpin, Meyen, Kutzing and 

 others. Greville, Meyen and Turpin gave the best 

 representations of them 5 Kutzing described them in 

 his Synopsis Diatomearum (as wretched a perfor- 

 mance as the drawings representing these animal- 

 cules) , without possessing the means required for 

 similar investigations , nor the knowledge of their 

 remarkable structure. 



Though incomplete, this short historical sketch 

 will suffice, I hope, for the intelligence of this Me- 

 moir, in which nothing farther is intended than the 

 natural history of the thermal animalcules, which I 

 observed last summer (1834), about the hot springs 

 of Carlsbad. 



