ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 



255 



Fig. CO. 



Gillett Achromatic Condenser. — Fig. 60 represents the Gillett achro- 

 matic Condenser, with fine adjustment, presented to the Society by the 

 President at its Meeting in December 1899 (see 

 this Journal, 1899, p. 679). 



Xeitz' Apparatus for drawing Macroscopic Objects. 



[This is, in fact, Dr. Wollaslon's camera lucida, 

 which w«s invented before 1807. and which 

 has been in use ever since.] 

 Centralbl. Bald. u. Par., 1899, pp. 765-C (1 fig.). 



(4) Photomicrography. 



Cobalt Blue Glass in Photomicrography.* 

 — Dr. James Wallace, of Philadelphia, points 

 out that by the use of blue glass in photomicro- 

 graphy the advantage of increased contrast is 

 often obtained. Sometimes, even, contrast is ob- 

 tained where none seemed to exist. Thus, for 

 example, in the case of a transparent body, such as a mosquito sting, 

 the yellow light of an ordinary lamp is very little affected by trans- 

 mission through the already yellow object. The yellow tint could in 

 the first place be increased by staining; and then, by the use of the blue 

 colour screen, it will be found to give a strong contrast in the photo- 

 graphic plate. Dr. Wallace has found the following method useful 

 for dealing with specimens mounted in balsam and improperly stained. 

 After removing the cover-glass he soaks the slide for a few minutes in 

 •chloroform, then dips it into a solution of picric acid in chloroform, 

 then places it in pure chloroform for five minutes, then in turpentine 

 long enough to get rid of the volatile chloroform, and finally remounts 

 in balsam. The strong contrast afforded by the picric acid staining and 

 the blue glass will give great satisfaction, and is highly recommended 

 for transparent objects. Potassium bichromate stains a good yellow in 

 aqueous solution, and brings out red corpu-cles in a very marked manner. 

 The advantage of picric acid is that it is soluble in chloroform, and can 

 be used for objects that have been already mounted in balsam. 



Bbinckerhoff, W. R. — A Non-vibratory Bench for Photomicrography. 



Journ. Boston Soc. Med. Set., III. (1899) p. 257. 



Gebharut, W. — Die mikrophotographische Aufnahme gefarbter Praparate. (The 

 Photomicrographie Reception of Coloured Preparations.) 



Internat. Phutcgr. Monatsschr. f. Med., 1899. 



Mathet, L. — Traite pratique de photomicrographie. Le microscope et son applica- 

 tion a la photographic des infiniment petits. Paris, 1899, Svo, 267 pp. 



W alms ley, W. H. — Photomicrography of Opaque Objects. 



[The author recommends the cultivation of this somewhat neglected subject.] 



Micr. Bull , XVI. (1899) pp. 45-6 



(5) Microscopical Optics and Manipulation- 



Brown, Theodore — Teaching the Laws of Binocular Vision. 



[The author describes an ingenious little apparatus for demonstrating to a class 

 the changes in the eye when an object is viewed.] 



Ena. Meek., LXX. No. 1814. pp. 439-40 (3 figs.). 



Micr. Bull., xvi. (1899) pp. 33-4. 



