On some Appearances, d'c. By G. F. Doivdestvell. 529 



Bacteria by their behaviour with the anilin dyes, by which, as by 

 methyl-anilin-violet, they are only stained faintly, like the red 

 corpuscles, while all forms of Bacteria, with a very few exceptions, 

 are readily and deeply coloured by this salt. Since the publication 

 of my own account of these bodies, their formation by the action of 

 some reagents has been observed and described by Dr. Stirling,* 

 and most recently in the blood in cholera as mentioned above. 



Conclusion. — Thus it is seen that there are several appearances in 

 the blood which may readily be mistaken for micro-parasites — to 

 use a comprehensive term — though the occurrence of the latter is 

 probably more frequent in abnormal and pathological conditions 

 than yet recorded. The increasing importance of this subject renders 

 it desirable that every observer should be familiar with these 

 appearances. I pass over here coagula, granules, and pigment, which 

 frequently occur in blood, the external form of which, if carefully 

 observed, sufficiently distinguishes them from the cells of living 

 organisms. 



But while, on the one hand, other bodies are mistaken for 

 Bacteria, in some cases veritable forms of the latter have been asserted 

 to be but fibrinous coagula, or in another case mere organic 

 crystals. 



Apart from the subject of pathological appearances and the 

 occurrence of foreign or parasitical bodies in it, the normal 

 form elements of the blood, after the observations of nearly 

 two centuries, are far from being exhaustively known ; the 

 varieties of the white corpuscles, of which there are several, 

 have been little more than suggested ; some phases in the evolu- 

 tion of the red corpuscles, as is asserted, have been but very recently 

 observed; whilst the functions, origin, and destination of Max 

 Schultze's corpuscles are scarcely more than conjecture: and 

 whilst, on the one hand, the micro-parasites of the blood, its 

 abnormal or pathological features, furnish a subject for examination 

 with, and an excellent test for, the highest powers of the Micro- 

 scope, its normal characters offer a field of investigation for 

 moderate powers, with a prospect of most valuable results, one that 

 is always readily available, but which has hitherto been somewhat 

 neglected by microscopists generally. 



* Journ. Anat. and Physiol., 1883. 



