lO ROYAJ^ SOCIETY OF CANADA 



that they are not numerous and are, moreover, restricted to certain 

 organs, such as lymphatic glands, liver, spleen, and kidneys, being, as 

 it were, filtered out of the blood. 



(6) That they are fibrin. 



1 do not find myself able to reach an entirely satisfactory con- 

 clusion on this point. In order to get some light u]3on it, I have 

 studied fresh blood taken from persons suffering from such diseases 

 as inflammatory rheumatism and lobar pneumonia, in which, as is 

 well-known, the blood clots very quickly. In such cases, after the blood 

 is drawn, fibrin makes its appearance in a few moments, in the form 

 of delicate, structureless, and colourless threads, having a highly 

 refractile contour. The process proceeds apace until, in every field of 

 the microscope, can be seen a mesh-work of interlacing fibrils. In no 

 case have I found that the " Dust-bodies " are more numerous in these 

 diseases than in healthy individuals, nor could I make out any particular 

 relationship between the deposition of the fibrin and the formation of 

 the " Dust-bodies." The fact, however, that the bodies become in- 

 creased in numbers in blood which has stood for some time, even when 

 clotting is absent and much delayed, and that certain of them are coloured, 

 as has been mentioned before, goes to indicate that they have little in 

 common with fibrin, and that certain of them are undoubtedly not fibrin. 



We pass on now to the much more difficult question indicated above, 

 viz., in how far the " Dust-bodies " are to be looked upon as derivatives 

 of the various normal components of the blood, red corpuscles, leucocytes, 

 hœmatoblasts, and serum (3, 4, 5). Farther, if such a relationship 

 can be established, is the process an active one, or a passive one, an 

 evidence oï tissue disintegration. 



My final conclusions on these points were only reached after several 

 months of study of the blood of man and of the lower animals, of certain 

 tissue-fluids and viscera. Being aware of the opinions previously ex- 

 pressed, that the " Dust-bodies " of the blood were granulations extruded 

 from the leucocytes, I first endeavoured to get positive information on 

 this point. To do this, I employed a warm stage and observed fresh 

 blood taken from various persons, and also from the frog and rabbit. 

 I had quickly been able to confirm the statement made before, that the 

 bodies were much increased in numbers in blood which has stood for 

 some time. This being the case, by prolonged observation it ought 

 to be possible to determine to what this increase was due. By 

 keeping the blood at a moderately elevated temperature, clotting is 

 delayed and the various cells preserve for a greater length of time their 

 natural characteristics. More particularly is this the case with the 

 leucocytes, which can be seen to retain their amoeboid properties for some 

 hours. Farther, the granules within the leucocytes are in active move- 



