ZOOLOGY A.ND BOTANY, MICROSCOPY, ETC. 413 



these objects. Mr. D. J. Scourfield, F.Z.S., F.R.M.S., made some 

 remarks on '"The Use of the Centrifuge in Pond Life Work." He used 

 a hand-driven form, running at about 70<hi r.p.m., with very small 

 tubes holding only about \\ c.cm. He had observed quite a number of 

 forms new to him, but could not yet say if they were really new ; 

 certainly some had never been named. He thought there was a cod 

 siderable held for work on what had been termed the " centrifuged 

 plankton." 



Barus, C. & M.— On an Adjustment for the Plane Grating similar to Rowland's 

 Method for the Concave Grating. 



[The authors give full particulars of a simple apparatus contrived and suc- 

 cessfully used by them.] 



Amer. Journ. Set., xxxi. (Feb. 1911) pp. 85-95 (6 figs.). 



B. Technique.* 

 (2) Preparing- Objects- 



Studying the Compound Eyes of Water-mites.f — K. Bedau fixed 

 the material (e.g. Notonecta glaaca, ffydrometra palustris, etc.) in four 

 kinds of fluid, but found that a mixture of 15 parts of 9(3 p.c alcohol, 

 30 parts distilled water, parts formalin, and 2 parts acetic acid gave 

 the best results. Perforations were made in thorax and abdomen to 

 allow the fixative to penetrate more easily. After from 6 to 12 hours, 

 the insects were removed to 70 p.c. alcohol for 6 hours, and then trans- 

 ferred to •' Seifenspiritus." in which they remained for 21 to 48 hours : 

 soap spirit is preferable to Eau de Javelle or Eau de Labarraque for 

 softening the chitin, and with the exception of fatty tissue has no dele- 

 terious action. The preparations were afterwards passed through up- 

 graded alcohols, and afterwards, using cedar-wood oil as intermediary, 

 embedded in paraffin. The sections were stained by Heidenhain's iron 

 method or with haemalum. For removing the pigment two fluids were 

 used. One consisted of 3 parts of nitric and 3 parts of muriatic acids to 

 150 of distilled water : the other was composed of 2 parts 96 p.c. of 

 alcohol and 1 part glycerin with some nitric acid. 



(4) Staining- and Injecting-. 



Studying the Cytology of Bacteria. J— C. C. DobeU obtained his 

 material from the intestinal contents of animals, mostly frogs, toads, and 

 lizards. He found that the usual methods of fixation may under suitable 

 conditions and with careful procedure be made to give excellent results. 

 Films should never be allowed to dry before fixation. When the medium 

 containing the bacteria is too watery, gelatin or albumen should be added 

 until a him of suitable consistence is obtained ; if the medium be too 



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

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

 (4) Staining and Injecting ; (5) Mounting, including slides, preservation fluids, etc. ; 

 (6) Miscellaneous. 



t Zeitschr. wiss. Zool., xcvii. (1911) pp. 418-20. 



% Quart. Journ. Micr. Sci.,lvi. (1911) pp. 395-506 (4 pis.). 



June 21st, 1911 2 e 



