1893.] MICROSCOPICAL JOUllNAL. S9 



DIATOMS. 



MoUer's Diatom Plates. — In the introduction to this volume 

 are the following- items of interest : 



The correct determination of diatoms is only possible when 

 based upon good illustrations, and these should receive the ut- 

 most care. One draughtsman treats his drawings diagrammati- 

 callv, another ornamentallv, and still another depicts only out- 

 lines, or thin sections, as if it were easy to gain a conception of 

 the whole therefrom. Some authors deem a rude, primitive 

 drawing sufficient when accompanied by a good description. 

 Instead of giving a representation of an ideal section of a simple 

 discoid form, a long, confusing explanation is furnished. While 

 a shoit description will be of value, a good illustration without 

 anv description is useful, w'hile the best description alone is in- 

 sufficient. The variation in drawings and illustrations of com- 

 parativel}- well-known species is so great that, were they placed 

 singly in the form of a type plate, the resulting confusion would 

 be simply appalling. In the interest of a more reliable literature 

 of the diatomaceae, we need a careful reproduction of those ac- 

 knowledged faithful drawings of all specific forms. This would 

 be of incalculable value to students of these most minute and 

 beautiful plant forms. If drawn to uniform scale of amplifica- 

 tion, and systematically arranged in tables, photography would 

 offer an excellent means of faithfully reproducing them. 



The introduction gives a history of the development of type 

 plates of diatoms, the first one being produced by Mr. Moller in 

 1S67 and it was sent to the famous algologist, Dr. L. Rabenhorst, 

 for identification. The preparation of similar plates, but on a 

 vastly larger scale, has been Moller's life-work. Of the more 

 famous specimens of his skill, a slide containing 720 separate 

 species of diatoms for the Army Medical Museum at Washington 

 was prepared in 1S69, one of S60 for Columbia College, New 

 York, in 1870, and one of 1,715 for Councillor de Capanema of 

 Rio Janeiro in 18S0. This last was intended as a present for the 

 late Emperor of Brazil. All these specimens of the minute pale 

 before Moller's last great microscopical slide, where, in a square 

 of about a quarter of an inch, he has in nine divisions and 133 

 continuous rows the enormous number of 4,036 different diatoms, 

 and with the aid of the catalogue each individual can be selected 

 and identified. 



MICROSCOPICAL SOCIETIES. 



San Francisco, Cal. — George Otis Mitchell, Sec'y 



February 75, i8gj. — The attendance of members and visitors 

 was large, and the meeting was informal. The Corresponding 



