ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 137 



p. Technique.* 

 (1) Collecting Objects, including Culture Processes. 



Collecting Diatoms.t — Mr. C. H. Kain, speaking of the bright- 

 brown patches of diatoms frequently seen covering the surface of mud, 

 recommends that they be collected in the following manner. 



Half fill a bottle with water. Touch one of the brown patches 

 lightly with the tip of the finger, and the diatoms will adhere ; then 

 place the finger over the mouth of the bottle and shake it. The diatoms 

 are, of course, washed off and remain. By repeating this process again 

 and again the water finally becomes quite brown. By the time the 

 collector reaches home the diatoms will have settled to the bottom, and 

 the water may be poured off and the diatoms cleaned. It is worth while 

 to examine under the collecting lens every promising patch of brown 

 mud, for very pure gatherings of quite different species may often be 

 collected within a few feet of each other. 



Culture of Unicellular Algse.| — Herr V. Jodin has made cultivations 

 of various species of Protococcus, Zygnema, &c., in artificial media, coDsist- 

 ing of solutions of the requisite minerals in distilled water. The most 

 suitable solution is the same as that used by Eaulin in his experiments 

 on Aspergillus niger. The solution is placed in flasks which are exposed 

 to the light and the carbonic anhydride is renewed in the air of the 

 flasks by an automatic generator. This simply consists of a flask filled 

 with a solution of ferric oxalate, connected with the culture-flask by a 

 bent glass tube passing through the caoutchouc stopper of the latter. 

 The ferric oxalate evolves carbonic anhydride on exposure to light. 

 Under favourable circumstances the crop obtained in several weeks' 

 exposure amounts to 10 grams of fresh algae or 1 to 2 grams of 

 dried product per litre. These cultivations are well adapted to throw 

 light on the chemical processes taking place in the green cell, since the 

 crops obtained are uniform and homogeneous, and are free from the 

 disturbing influences arising from the differentiation of organs and the 

 migration of proximate principles in the higher plants. The author 

 concludes by stating that the proportion of nitrogen in Protococcus 

 varies from 1 • 43 to 6 • 67 per cent, of the crop. The conditions of 

 assimilation of this element are still under experiment. 



S Y K A, J. — Ueber Milchreis, einen neuen festen Nahrboden. (On rice-milk, a new 

 solid culture medium.) 



Deutsch. Med. Wochenschr., 1888, p. 833. 



(2) Preparing Objects. 



Reaction of Elastic Fibres with Silver Nitrate. § — Prof. C. Mar- 

 tinotti describes a new method for demonstrating elastic fibres in the 

 various tissues and organs. 



Fresh tissue in pieces of 2 to 3 ccm. are placed in a 2 per cent, solu- 

 tion of arsenic acid for 21 hours, but if parts attached to bone are to be 



* This subdivision contains (1) Collecting Objects, including Culture Pro- 

 cesses; (2) Preparing Objects; (3) Cutting, including Imbedding and Microtomes; 

 (4) Staining and Injecting ; (5) Mounting, including slides, preservative fluids, &c. ; 

 (6) Miscellaneous. t Bull. Torrey Bot. Club, 1888, pp. 128-31. 



% Ann. Agronom., xiv. pp. 241-5. See Journ. Chem. Soc, 1888 fAbstr."). 

 p. 1124. ^' 



§ Comm. alia R. Accad. di Med. di Torino, 1888, pp. 5-15, Cf. Zeitschr f. 

 Wiss. Mikr., v. (1888) pp. 521-2. 



