6 ROYAL SOCIETY OF CANADA 



wiped off with a clean linen rag. It is important not to employ too 

 much blood. Only a thin film should be made, which should, however, 

 reach to the edge of the coverslip. This end is best achieved by using 

 round coverslips {No. 1) of a constant diameter, and by collecting the 

 blood with a standardized platinum loop, which has been made to 

 hold the necessary quantity. When it is desired to mix the blood with 

 certain reagents, as, for instance, saline solution, water, acetic or osmic 

 acids, or certain dyes, a loop of half the size has been found convenient. 

 Thus one small loopf ul of blood, with one loopful of reagent, will give 

 the required amount. If there should be any excess of blood, it should 

 be wiped away from the edge of the coverslip with a little clean filter 

 paper. The coverslips may then be ringed about with vaseline, although 

 this is not essential. Both coverslips and slides should be absolutely 

 free from grease and dust. In practice a standard loopful of blood is 

 taken from the patient and placed in the centre of a standard No. 1 

 coverslip, which is then quickly lowered into place on a clean slide. 

 Care should be taken not to squeeze the film. The film may then be 

 examined as it is, or after warming in an incubator, or, again, on a 

 warm stage. 



The various points to be referred to can, in the main, be made out 

 by the use of any good l-12th oil-immersion lens, but for careful study 

 an l-18th or l-20th is necessary Avith a ISTo. IV eye-piece. For 

 illumination, the best results are obtained by employing the Auer or 

 Welsbach Light, with or without a disc of blue glass in the sub-stage. 

 The concave mirror should be used and the condenser lowered, so as 

 to cut off part of the- light. By this means very clear pictures are 

 produced and the colour and form of the particles are much better 

 brought out. 



As one result of my inquiries, I can amply confirm the statements 

 of earlier observers as to the constant presence of these minute bodies 

 in the blood of human beings, both in health and disease, and also in 

 that of many of the lower animals. When viewed with the highest 

 powers of the microscope, they appear as highly refractile particles of 

 varying size and shape, appearing alternately light or dark as they bob 

 up and down and in and out of focus. Their size varies within wide 

 limits. In blood, which has stood some time, circular bodies, perhaps 

 one quarter to one half the diameter of a red corpuscle, can often be 

 seen, which, from their shape and colour, are obviously portions of red 

 cells, or schistocytes. From this form, on the one hand, to the " dust- 

 body," on the other, all possible gradations of size and shape exist. 

 From the point of view of morphology alone, we have not found it 

 possible to draw a hard and fast line between the '^ dust-bodies " and 

 schistocytes or microcytes. The typical " dust-body," Blutstaubchen of 



