1893.] MICUOSCOl'ICAL JoriLNAL. S9 



DIATOMS. 



Moller's Diatom Plates. — In the introduction to tliis vcjlunic 

 arc the lollovviiig items of interest : 



The correct determination of diatoms is onlv possible when 

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

 most care. One draughtsman treats his drawings diagrammati- 

 cally, another ornamentally, 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 simjile 

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

 a short tlescription will be of value, a good illustration without 

 any description is useful, while the l>est description alone is in- 

 sufficient. The variation in drawings and illustrations of com- 

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

 singlv in the form of a tyj^e plate, the resulting confusion would 

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

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

 knowledged faithful drawings of all specific forms. This would 

 be of incalculal)le value to students of these most minute and 

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

 tion, and systematically arrangetl 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 AloUer'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 860 for Columbia College, New 

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

 Rio Janeiro in iSSo. 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. 



MI(lK)S(OrT( AL SOdKTIES. 



San Francisco, C.vr.. — Geohge Otis Mitchell, Scc'v 



February yj, iSg^. — The attendance of members and visitors 

 was large, and the meeting was informal. The Corresponding 



