[nicholls] significance OF "DUST-BODIES" OF THE BLOOD 9 



fact that they are present in blood which is removed after death from 

 the heart by inserting a sterilized pipette through the auricular wall, 

 where there is no possibility of such contamination. Finally, the number 

 of the " dust-bodies " increases when the preparation is kept for some 

 time. In pleural and pericardial inflammatory exudates, I have found 

 them in great numbers, to such an amount, in fact, that their presence 

 could not be accounted for on the theory of contamination. 



(2) That they are fat. 



They are beyond question not fatty particles imported into the 

 blood in the process of making the puncture, Which, of course, passes 

 through a pad of subcutaneous fat of some thickness, for they are 

 present in the blood and lymph taken after death from parts where 

 there is no fat. Again, they do not altogether resemble fat, since 

 many of the larger particles present a yellowish-green colouration, while 

 others are distinctly pinkish, as if they contained hœmoglobin. Finally, 

 I have satisfied myself that they do not stain black or brown on the 

 addition of osmic acid. 



(8) That they are protozoa, micramœbge, malarial parasites, or 

 bacteria. 



This possibility is easily disposed of. According to my observa- 

 tion, the " Dust-bodies " possess neither nuclei, vacuoles, nor granular 

 pigment, and have no independent motility. Amseboid movement has 

 not been observed, and they do not go through the -phases characteristic 

 of the malarial parasite. They are, farther, to be observed in the 

 blood of all human beings, both in health and disease, in many instances 

 where there was no possibility of malarial infection, and in many of 

 the lower animals. Some, at first glance, might be mistaken for 

 bacteria, but with care certain differences can be made out. I find 

 that on the addition of certain bacteria, such as, for example, the 

 staphylococcus aureus, b. anthracis, b. tuberculosis, or even such actively 

 motile forms as the b. tv'phi, to fresh blood the BroTi\Tiian movement and 

 motility are greatly retarded or even checked completely, pointing to 

 an inhibitory action of the blood serum which water and nutrient fluids 

 do not possess. On the other hand, the movement of the " Dust-bodies " 

 is extremely lively. Again, the larger, rod-like, bodies, which might 

 possibly be mistaken for bacilli, are of a greenish-yellow colour, sug- 

 gestive of the appearance of the red-blood corpuscles. The pinkish 

 colour of certain other of the bodies is unlike that of the known bacteria. 

 Moreover, it is hard to think that bacteria could he present in the blood 

 in such large numliers as the frequent presence of the " Diist-bodie.^ " 

 would indicate, without grave disturbance of the animal economy. It 

 is true that recent observations go to prove that living bacteria are 

 present in the tissues of healthy individuals, but investigation shows 



