118 FArj.AC'IES AND PUZZLKS IN BLOOn EXAMINATION 



of typhus fever jmtieuts. One has meiitioned the chain, fliinib-bell, droplet and hlaiuont 

 phenomena exliibited by red cells brought under the influence of heat (Fig. 30). 

 Crawley has recently described similar changes seen in blood %vith dark-tield illumination 

 and has termed tliem beaded threads. I have also observed these and I was at 

 first inclined to think that the proximity of a liot lamp, the source of light, had 

 sometiiing to do witli their presence, but recent work witii a better api)aratus has 

 negatived this view, and it is evident that they can l)e seen by the dark-field method 

 wiien there is no possibility of the blood temperature having been raised, at least to 

 Free flaRi-iia any appreciable extent. Crawley also noted free flagella in the blood. These are 

 probably of the same nature as the beaded thi'eads, and are, I expect, what I have 

 termed filaments, but one must not forget that under artificial conditions lymphocytes 

 (Ross and Maealister) and myelocytes (Buchanan) may flagellate. Such a phenomenon may 

 be induced by certain excitants, atropine and methylene blue, as well as by a cancerous 

 plasma. This being so, it is possible that certain pathological conditions of the blood may 

 Ijring about tiie flagellation in white cells and that free flagella may account for some errors 

 of diagnosis. Indeed, Crawley, I find, mentions their occurrence. Bodies showing 

 pseudopodia have also been seen in normal blood under dark-field illumination, and thereby 

 a fallacy was cleared up, for at one time they were supposed, by Koch and Kleine, 

 to be associated with piroplasmosis in dogs and cattle. They are only greatly altered 

 blood cells, and Crawley believes them to be more probably derived from erythrocytes than 

 from leucocytes. Crawley has also some interesting notes as regards the behaviour of both 

 red cells and white cells under this form of examination, and I see he notes the stimulating 

 effect of the heat of the dark-tield method upon the leucocytes. The vesicles which he 

 describes as occurring in red cells are, I think, analogous to the bodies I found in the fresh 

 blood of fowls and which I fear I mistook for a special form of intra-corpuscular spirochajtal 

 inclusion [Journal of Tropical Medicine and Hygiene, October 1, 1909). I have certainly seen 

 sucli bodies grow smaller and become the nebulous clouds of which he speaks. He can give 

 no explanation of this phenomenon, and neither can I, but I was able to recognise I had 

 made an error by finding similar bodies in the blood of gerbils, which, though inoculated 

 with spirochaatal blood or blood supposed to contain spirochictes, never showed any sign of 

 iUness. The trouble is that the true intra-corpuscular forms look exactly like the pseudo 

 forms. I believe the fact that the latter are motile, a point mentioned by Crawley, may 

 serve to distinguish them. Reference to this matter will also be found in the paper entitled 

 " Spirocha-tosis of Sudanese Fowls," page 84. Blood plates are better studied by 

 transmitted light, but it is said that the dark-field method has shown tliat mononuclear 

 leucocytes break up into bodies like hamatoblasts, an observation which, if confirmed, 

 while not of much importance in the examination of fresh blood specimens, may well 

 explain some puzzling features met with in stained films of animals' and birds' blood. 



A suggestive paper is that on leucocyte degenerations in the cerebrospinal fluid by 

 Kve. The illustrations he gives show that if similar changes can occur in the blood, and 

 under certain conditions nothing is more likely, then there is every probability of the 

 resulting motile, globular, hyaline and flagellated bodies which are produced, being 

 mistaken, as they were at first by him, for extraneous protozoal contaminations. 

 haii.ici.-> in 2. We pass now to the examination of fallacies and puzzles in the stained blood, and 



stained blood ^^ ^^^ ^^g jjg^e only considering those of an autogenetic nature, it will be as well to take 

 up in turn each of the main groups of blood elements and see how it may deceive or 

 trouble the observer. Pride of place may be given to the little blood platelets, for 

 I lielieve thcv are a more common source of error than anything else in the blood. 



