308 ^ The Microscope. 



I can not consent to close without alluding to the excellent work 

 of American students of the protozoa already to our credit. We all 

 know Dr. J. W. Bailey as a pioneer in American microscopy; as one 

 who acquired a high degree of excellence in the microscope and was 

 able to obtain from it its very best performance, and who did much 

 toward fixing a high standard for our opticians and investigators. 

 He was an industrious student of minute types of life, and the first, 

 I think, to publish original observations on the protozoa in this 

 country. His papers relating to these organisms occur in the Smith- 

 sonian Contributions to Knowledge, beginning in 1855. These con- 

 sist of species identified, with descriptions of a few species of rhizo- 

 poda and infusoria. In connection with the first list is also one by 

 Thomas Cole. Dr. Bailey remarks that " Mr. Cole is, I think, the 

 first in this country to make a systematic study of the soft-skinned 

 infusoria." Both lists contain the names of species which are among 

 our most interesting ones. 



Undoubtedly, the most brilliant discovery thus far stands to the 

 credit of Prof. H. J,. Clark. He was a student and, I think, an 

 assistant, of Prof. Agassiz; hence, necessarily, a thorough investi- 

 gator. Not feeling satisfied with the performance of the objectives 

 made for Prof. Agassiz by Oberhaeuser, and the best to be obtained 

 of that makei', he secured those by C. A. Spencer and R. B. ToUes. 

 With these he was able to demonstrate structure in the protozoa not 

 previously suspected. I refer, principally, to the discovery, in 1868, 

 of the "collar of certain flagellate monads." This was a triumph for 

 American objectives as well as for an American naturalist. The 

 many beautiful forms discovered in the last two decades now consti- 

 tute the order coano-flagellata. He also discovered at this time 

 that the tubular passages of sponges were lined with similar collared 

 monads; hence, he announced the protozoic nature of the porifera, 

 a proposition with which but few naturalists at present accord. This 

 is mainly, it seems, because the supposed embryology of the sponges 

 allies them to the metazoa. 



If these phenomena are finally interpreted differently, the 

 sponges may yet be relegated to the protozoa. So far as the fresh- 

 water representatives are concerned, excepting the so-called embryo- 

 logical characters, they appear to be protozoic; especially since the 

 discovery of proterospongia, a genus of undoubted coano-flagellate 

 monads which secrete a mucilaginous matrix for the shelter of the 

 colony. Representatives of the genus are known both iu Europe 

 and America. 



