298 Notice of Ehrenberg's Memoir on Microscopic Life. 



left them as mere subjects of amusement, although at present 

 regular professors of electricity and magnetism are established at 

 all the universities of the civilized world. 



The author hopes that the continuation of his labors will show, 

 that however much that is untenable may have been presented 

 in science of late, the objects and results of microscopic research 

 are by no means such as to prevent the strictest critical examina- 

 tion, and that they can even be subjected to the best of all tests, 

 ocular demonstration. 



He then alludes to his discoveries with regard to the important 

 influence which animalcules have had in filling up streams and 

 harbors, and in the formation of deltas, and states that observa- 

 tions have now rendered it more obvious how rock-masses which 

 are wholly or partially crystalline, may have resulted from the 

 solution and change of minute siliceous and calcareous organ- 

 isms. 



II. Review of the materials. — The author in consequence of the 

 various relations of microscopic life to the great field of nature, felt 

 induced to compare the facts observed in Europe with the condi- 

 tions of other parts of the world, and, accidentally, the American 

 forms were the first examined. Among the materials for this 

 study of the American forms, were specimens of edible clay 

 from the banks of the Amazon, furnished by Von Martius; spe- 

 cies collected in a living state in Mexico by the author's brother, 

 Carl von Ehrenberg ; earth attached to plants in herbaria; and 

 "a whole box full" of fossil animalcules sent from the United 

 States by Mr. B. Silliman, junior; by Professors Silliman, Hitch- 

 cock and Bailey ; and a number of the living species of West 

 Point were received directly from Prof. Bailey in the year 1S42. 



From the results of the investigation of these materials, Ehren- 

 berg is enabled to present a view of the minutest forms of animal 

 life, extending from the Falkland Islands on the south, to Labra- 

 dor, Kotzebue's Sound, Iceland and Spitzbergen on the north. 



I [I. Enumeration of the American forms, according to the 

 date of observation. — This detailed enumeration of species from 

 different localities is full of interest, but our limits compel us to 

 give but brief notices of many of the localities, and to confine 

 our attention chiefly to the most important observations concern- 

 ing the localities in the United States. We remark however that 

 among the species detected with sea Confervae from the Falkland 



