BACTERIOLOGICAL EXAMINATION 291 



number of diseases in which, particularly in especially severe cases, the 

 pathogenic agents enter the blood. Formerly we contented ourselves with a 

 microscopic investigation of fresh or stained blood to determine the presence 

 of bacteria. But this process should only be resorted to for the determination 

 of the spirilli of relapsing fever, or, perhaps, of the bacilli of anthrax. In 

 other cases it may lead to errors, first because of the small number of germs 

 that may be present, and, secondly, because confusion with accidental bacterial 

 contaminations may readily occur. It is therefore advisable to puncture a 

 vein of the arm under strict antiseptic precautions, to withdraw 1 to 2 c.c. 

 of blood, and to prepare cultures, best in bouillon, or to determine by animal 

 experiments the probable presence of pathogenic bacteria. 



In this manner we are able to determine with certainty in the circulating 

 blood the presence of streptococci, staphylococci, pneumococci, the bacilli of 

 enteric fever, of the plague, of tuberculosis and others. [Typhoid bacilli have 

 repeatedly been cultivated from the blood of doubtful feljrile cases before 

 the Widal reaction had appeared. Hence this procedure may be of great 

 value in obscure cases. The same is true of the cultivation of pneumo- 

 cocci from the blood in obscure pneumococeus infections and " central pneu- 

 monias." — Ed.] 



The determination of the pathogenic agents just mentioned can only be 

 designated as an auxiliary factor in diagnosis, but the recognition of spirilli 

 in the blood is the only means for a positive diagno- 

 sis of relapsing fever. As a rule this determina- 

 tion is very easy, for the peculiar curved form of 

 the spirilli (see Fig. 17) precludes confusion with 

 other organisms. Their number is usually very 

 large; our detection of them is greatly facilitated 

 by their motility, and, finally, they stain readily 

 with various anilin colors, for example, intensely Oq 

 with fuchsin, so that they may be easily found in a O 

 dry preparation even if present in the blood in 

 very small numbers. t. ,., ■□ -c^.r^^ 



V, , n . ,1 T . ,1 i- 1 Fig- 17.— Relapsing Fevek 



Frobably m no other disease is the practical spirilli. (After v, Jaksch.) 

 importance of blood examination greater than in 



malaria. This is naturally not the place in which to describe the entire devel- 

 opment of the malarial parasite, nor even to mention all of the varieties which 

 occur in the blood, as a special article has been devoted to this important sub- 

 jeet.i Here it need only be mentioned that, in many cases, we should look 

 for the Plasmodia in the blood, and should familiarize ourselves with the most 

 important points in the technic of examination. 



In the investigation of the blood for malarial parasites for diagnostic 

 purposes, the stained dry specimen is unquestionably the most suitable, and 

 we shall explicitly describe its preparation in another place. For when very 

 few parasites are in the blood, this method alone assures their detection, and 



1 Compare the article by Loeffler in the volume on " Infectious Diseases." 



