360 TIMOTHY RICHARDS LEWIS. 



Spirilla — fine, more or less flexible, spiral filaments, which 

 manifest well-marked screw-like movements (fig. 1, e.). 



It may be mentioned, in passing, that examples of each of 

 these forms may commonly be detected in the muco-salivary fluid 

 from the mouth of healthy persons. 



The question which naturally suggests itself now is : Under 

 what condition are organisms of this character found in the blood ? 

 M. Pasteur states that the blood in health is absolutely free from 

 anything of the kind. His words are : " Le sang d'un animal 

 en pleine sante ne renferme jamais d'organismes microscopiques 

 ni leurs germes."^ Dr. Beale, on the other hand, says, " The 

 higher life is, I think, interpenetrated, as it were, by the lowest 

 life. Probably there is not a tissue in which these germs are 

 not ; nor is the blood of man free from them.'"^ It may appear 

 strange that the satisfactory settlement of a question, apparently 

 so very simple, should hitherto have proved impossible, and that 

 many eminent observers should have arrived at opposite conclu- 

 sions regarding it. It may be that to a certain extent both 

 classes of observers are in the right, for if, as is not uncommonly 

 affirmed, very many of these extremely minute organisms con- 

 stantly find their way into the circulation through the lungs and 

 pass through the walls of the intestinal tract along with the food 

 (that bacteria pass with fluids through a membranous septum is 

 a well-ascertained fact, as also that they will pass through porous 

 earthenware and other filtering media), it is very certain that 

 their existence in the plasma of healthy blood is of comparatively 

 short duration. 



This point has been definitely settled as the result of observa- 

 tion by many pathologists, and Dr. Douglas Cunningham and 

 myself were, some years ago, able to satisfy ourselves that bacteria, 

 vibriones^ bacilli^ and so forth, very speedily disappear from the 

 liquor sanguinis, even when introduced into it during life in 

 considerable numbers. Out of forty-nine experiments which 

 were conducted by us with a view of clearing up this matter, 

 twelve of the animals were examined within six hours of the 

 organisms being injected into the veins, and bacteria, &c., were 

 found to be present in seven, or at the rate of about 58 per 

 cent. ; and out of thirty examined within twenty-four hours, 

 their presence was detected in fourteen, or 47 per cent. ; whereas 

 in nineteen specimens of blood derived from animals which had 

 been inoculated in this manner from two to seven days previously, 

 these bodies could only be detected in two of them, or a little 

 over 10 per cent., just 6 per cent, higher than we had observed 

 to be the case out of a number of ordinary preparations of 



1 'Comptes Rendus,' t. Ixxxv, p. 108 j 16th Jiilj, 1877. 



2 'Disease Germs,' 1870, p. 64. 



