22 REVIEW — TROPICAL MEDICINE, ETC. 



Blood— and move the specimen until the whole field of view is occupied by a portion of the coloured 



continue/ material. If necessary an oil immersion must be used. Eeniove the eye-pieco and replace 

 by a micro-spectroscope. If the stain is of blood the two absorption bands of 

 hiCmochromogen will be seen. If invisible, as a result probably of commencing putrefaction, 

 a drop of a 10 per cent, solution of potassium cyanide should be allowed to fall on the stain, 

 and the bands will appear somewhat nearer the red end of the spectrum than usual. The 

 boiling is to prevent the colouring matter going into solution and being so diluted that the 

 bands could not be seen. Stains on weapons or jewellery should first be wetted with 

 ammonium sulphide. A small portion may then be scraped off with a knife and treated 

 as above. 



A new method of employing the guaiac test had been introduced by Holland'* owing to 

 the difficulty of getting really old turpentine or good peroxide of hydrogen. He employs as 

 an oxidising agent, sodium perborate, made from sodium dioxide and boric acid. Freshly 

 broken pieces of guaiac resin are dissolved by boiling with alcohol in a test-tube for a few 

 minutes till the tincture is yellow. The suspected material is then cautiously mixed with a 

 drop or two of the guaiac solution to make a milky mixture. This is brought in contact with 

 a fragment of sodium perborate on a white plate. 



If the proportion of blood bo large, the white perborate turns blue in a few minutes and 

 remains blue until the drying of the guaiac leaves a yellow residue which changes the blue to 

 green. If small, the white perborate turns a pale blue which becomes green as the guaiac 

 dries. The test is simple and delicate, but is, of course, liable to the fallacies belonging to 

 the ordinary guaiac reaction. 



Turning to clinical methods, we find that Leishman^ describes a simple method of 

 enumerating leucocytes. 



Two pipettes are employed — one, an ordinary one-cubic centimetre pipette graduated in 1/lOOths of a 

 cubic centimetre ; the other, a capillary pipette to deliver five cubic centimetres. This quantity of 

 the blood to be tested is taken up in the capillary pipette and at once diluted 200 times by being blo^vn 

 out into a watch-glass containing 995 cubic millimetres of water. Hjemolysis occurs but the leucocytes 

 remain unaltered. Stir, shake and, after the capillary pipette has been washed and dried in the flame, take 

 up with it two successive volumes of five cubic millimetres each and discharge them side by side as small 

 drops on a clean slide. Allow these to dry and stain with Leishman's stain. 



Count all the leucocytes in each drop with the help of a ruled cover-glass, prepared by allowing a drop 

 of Leishman's stain to evaporate on the well-polished surface of the glass and ruling on the thin lilm which 

 is left a series of parallel lines with the point of a sharp needle, A drop of cedar oil is placed on the stained 

 drop film and the cover glass dropped on it, ruled surface downwards. Count, with a 2/3rd inch lens, the 

 leucocytes in all the drops, representing the 10 cubic millimetres of the diluted blood. Multiply by 20 and 

 you get the number per cubic millimetre of undiluted blood. The error, compared with a Qower's 

 haemocytometer count, seems to be about minus 5 per cent., %vhich may be allowed for or neglected. 



General clinical methods of enumerating leucocytes, including new and simplified 

 procedures, are described by Turton," but lack of space forbids a review of his paper. 



Of more interest to the ordinary blood examiner are certain papers on Htemiconia, what 

 used to be called blood dust. Love* draws attention to the special prevalence of htemiconia 

 in typhus fever and describes four forms of bodies. 1. Protoplasmic bodies with bright 

 retractile spots whose origin presents no difficulty, as staining shows them to be derived from 

 fragmented neutrophile cells. 2. Small, round, highly refractile bodies from 0-5 to 1/j in 

 diameter, and appai-ently motile. 3. Eod-like bodies, also apparently motile, from 0-5 to 2/x 

 in length. 4. Dumb-bell forms, from 2 to ijx in length, and apparently motile. He 

 regards the last three as of the same class and mentions their incessant dancing movements 

 and the fact that they cannot be stained. From this, and from their disappearance during 

 the fixing process, he concludes that they cannot be derived from the disintegration or 

 fragmentation of leucocytes or red blood corpuscles. 



Porter' describes five forms, a. Greyish-blue, flagellated bodies of indefinite shape and 

 possessing a twisting or rotatory movement. 6. Bodies like a large diplococcus with rapid 



' Holland, J. W. (June 8th, 1907). Journal of American Medical Association. Chicago. 



* Leishman, W. B. (March 31st, 1906), "A Simple Method of enumerating Leucocytes." Lancet,-^. 905. 



' Turtou, E. (February 25th, 1905), "CUnical Methods of Enumerating Leucocytes." British Medical 

 Journal, p. 410. 



♦ Love, A. (December 29th, 1904), " Hoemioonia." Lancet, p. 1781. 



' Porter, P. (December 21st, 1907), " Observations on Blood Films, with Special Reference to the Presence of 

 Hsemiconia." British Medical Journal, p. 1773. 



• Article not consulted in the original. 



