ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 535 



method S. pallida appears as a shining silver-like thread with corkscrew 

 turns lying in a black or blackish backs-round. In order to obtain a 

 satisfactory result it is necessary to make the films (wet or dry) from 

 the serum only, or as little contaminated with red corpuscles as possible. 

 Fixed films are best stained with Leishrnan's stain, which has less 

 tendency to deposit than Giemsa's ; but many anilin pigments made up 

 with phenol answer very well. The serum may be stored up in sealed 

 capillary tubes. 



Detection of Seminal Stains on Clothing.* — Corin and Stokis have 

 recentlv shown the affinitv of spermatozoa for staining agents containing 

 iodine such as Bengal rose and especially erythrosin. This last substance 

 is a brown powder, forming in water a solution stable in the presence of 

 ammonia. It is used in the strength of 1 in 200 in pure ammonia 

 solution, in which form it keeps indefinitely. In examining a supposed 

 seminal stain a single fibre of the fabric is removed with scissors, and 

 immersed in the staining solution for 1 or 2 seconds. It is then trans- 

 ferred to a drop of distilled water on a slide which is placed on a dark 

 background, and the fibre is thoroughly teased with needles. It may 

 then be covered and examined with a low power, when the fibres of 

 cloth being unstained it is easy to pick out masses of red points, which 

 on higher magnification are seen to be the heads of the spermatozoa. 

 The presence of the ammonia prevents the staining of the vegetable 

 'fibres while the spermatozoa are deeply stained, and their tails may be 

 easily seen by using a small diaphragm. When the seminal stain has 

 dried into the cloth the tails of the spermatozoa may be more difficult 

 to demonstrate, but in this case a deeper coloration may be obtained 

 by immersing the fragment of cloth before staining for a few minutes 

 in Midler's fluid (bichromate of potash 1 part, sulphate of soda 2 parts, 

 water 100 parts). This method is applicable to linen, cotton, silk and 

 wool fabrics. The age of the stain seems of little consequence,' sperma- 

 tozoa being readily found in material 10 years old. The ervthrosin 

 solution stains most of the cellular structures of animal origin likely to 

 be met with in suspected clothing such as pas, and epithelial cells, but 

 while it shows these very clearly it does not detract from its value in 

 the detection of spermatozoa, the appearance of which is characteristic. 



Re id, E. E. — Electrically -controlled Gas-regulator. 



[Can be made quickly and easily out of materials at hand in the chemical 

 laboratory, and is easily cleaned.] 



American Client. Jowrn., xli. (1909) pp. 148-52 (2 figs.). 



* La Presse Medicale, Feb. 13, p. 120. See also Med. Record, 1909, p. 207. 



