ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 143 



Method of preparing Potatoes for Bacterial Cultures.* — In order 

 to meet the objections raised by E. Esmarch to the ordinary method of 

 potato cultivation, Mr. M. Bolton, as he could not procure the Esmarch 

 ceils in America, adopted the following method in place of that proposed 

 by Esmarch. 



In test-tubes 4^ in. to 5 in. long, of 1 in. or more in diameter, were 

 accurately adapted pieces of potato 2-3 in. long. The skins having 

 been removed, the potatoes were cut up in an ordinary apple-corer. It 

 was found advisable that one end of the potato-pieces should bo cut 

 obliquely, so as to offer as large a surface as possible, as in agar or serum 

 tubes. At the bottom of the tube a drop of water is placed in order to 

 prevent the potato from drying up. The tube is then carefully sterilized 

 by steam. 



Cultivation-bottle.f — Dr. H. Wilfarth uses, instead of the ordinary 

 plate, for separating different kinds of bacteria, a flat flask of thin glass, 

 much like an ordinary brandy bottle. The sides are round, parallel 

 to one another, about 2-2g cm. apart, and run pyriformly to a neck 

 about 16-18 mm. wide, and sloping obliquely upwards. The neck is 

 closed with a cotton-wool plug. The sterilized medium having been 

 introduced and the inoculation made, the flask is laid on the flat side, 

 and for microscopical examination under moderate powers it is turned 

 over so that the gelatin layer is uppermost. 



For liquefying colonies and for agar cultivations the bent neck of 

 the flask renders it inconvenient for removing colonies for inoculation. 

 The flask is filled by means of a separating-funnel, which only allows a 

 certain quantity to flow in at a time. 



Collecting and Cleaning Diatoms. $ — Mr. K. M. Cunningham, who 

 states that he has been able to demonstrate 300 distinct species of 

 diatoms from the immediate neighbourhood of Mobile, says that the first 

 requisite in the preparation of marine diatoms is to secure a quantity 

 of mud, and the subsequent treatment as pursued by the writer is as 

 follows : — 



Take at least half a pound of hard or soft mud to begin on, and 

 soften it into a uniform liquid paste, and to hasten and assist its 

 liquidity, add about a teaspoonful of aqua ammonia?, which liquid will 

 be useful in the initial steps of cleaning, as it cuts and dissolves slimy 

 and gelatinous impurities, and cleans the sand-graius, and enables the 

 bulk of the material to be cleaned to settle quickly and compactly, as 

 well as having distinct lubricating properties. Next transfer the liquid 

 mud to a suitable vessel of tin or china of at least six or more inches in 

 diameter, and not over 5 or 6 in. deep ; put therein as much liquid 

 mud as will fill 1 in. in depth, and fill up the vessel with clean water, 

 and stir rapidly the contents to liberate the flocculent matter from 

 the heavier contents. After allowing the contents to settle for ten 

 minutes, with a piece of rubber tubing, at least 18 in. in length, 

 siphon off the water to within 1/2 or 3/4 in. of the bottom of the 

 vessel, renew the water, and then stir quickly, and after five minutes 

 again siphon off the water to within 1/2 in. of the bottom. The 

 sediment left is transferred to any shallow tin or other vessel for con- 

 venience. 



* Medical News, 1887, i. p. 318. t Deutsch. Med. WocLenschr., 1S87, No 28 

 X Microscope, vii. (1887) pp. 331-C. 



