150 THE AMERICAN MONTHLY [July, 



dition, are efficient media for the growth of microbes detrimental to 

 health, particularly in cities of warm climates. But few of our cities 

 in warm climates have as wholesome water as is needed for domestic 

 purposes, being so filled with germs as to be unsafe for many persons 

 to drink without sterilization. The indifference of the people to these 

 important matters is largely due to the fact that their nature and bearing 

 are not understood. The reasons why the streets should be clean, the 

 water wholesome, and that there should be efficient sewerage in 

 our cities, are evident to health boards, but it needs enlightened 

 public opinion to more thoroughly carry out the demonstrations of the 

 microscope. 



The Classiflcation of Diatoms. 



By C. M. VORCE, 



CLEVELAND, OHIO. 



In the very interesting paper of Rev. F. B. Carter in the Mayy^z/r- 

 nal I notice the omission of all reference to three genera of diatoms, 

 some or all of which are sure to be found in the collections of most be- 

 ginners who give the study of the diatoms any but the most cursory 

 attention. These genera are Actinocychis^ Amphiprora^ and Rhizoso- 

 lenia. So far as I have heard, the first and last of these are only found 

 in the waters of the great lakes, and chiefly in Lake Erie, but all are 

 liable to be found in other bodies of fresh water, and should be in- 

 cluded among the fresh-water forms. 



Actinocyclus has the typical markings described for the fossil form, 

 with a circlet of extremely minute intra-marginal spines, and is inflated, 

 or kettle shaped. A. niagarce is the fresh-water species, and may be 

 looked for, although it is rare, in the waters of the great lakes from 

 Chicago or Duluth to Oswego, and in the St. Lawrence river. 



Amphiprora^ as described by Mr. Carter, is best represented in 

 fresh water by the common and widely distributed^. or?iata, and may 

 be recognized by presenting the shape of the figure 8, or that of a jews- 

 harp or fiddle, according to which side is viewed. 



Rhizosolenia^ with the characters described, may be looked for in 

 the waters of all the great lakes, and the form R. eriensls is often ex- 

 cessively abundant in the waters of Lake Erie. 



It seems to me the classification of H. L. Smith would have been 

 preferable to that of the Micrograpic Dictionary, although the latter, if 

 closely studied, will help the beginner to a decision on most of the 

 forms he will encounter. 



A New Bureau. — Secretary of Agriculture Rusk has recently put J 

 in working order his new bureau in Chicago for the microscopic ex- | 

 amination of hog products for export. He selected a corps of thirty 

 microscopists, fifteen men and as many ladies, and they were set to 

 work under the direction of Drs. John Michels, of New York, and F. 

 H. Bernard, of Pittsburg, microscopical experts. The force will be in- 

 creased until it is large enough to examine a piece of the diaphragm i 

 and of the tenderloin of each hog killed. Those found to be diseased 1 

 will be condemned. 



