282 APPLIED BACTERIOLOGY 



The main distinction betiveen the benign and malign 

 species is that in the case of malign parasites flagella are 

 produced from crescent bodies, while in the case of the 

 benign 'parasites they are produced from simple spheres. 

 Crescent bodies are alwaj's found in malign fevers, though 

 not in the early stages ; they continue in the blood for 

 many days, and are not affected by quinine. 



Surgeon-Major Eoss is of the opinion that when it 

 becomes more general to use the microscope as an aid to 

 diagnosis in all cases of fever (speaking of countries where 

 malaria is prevalent), it will be found that a very much 

 larger number of cases are due to the parasite than have 

 hitherto been supposed. Another point of practical im- 

 portance, in his opinion, is that while crescents are 

 swarming in the blood (after an attack of fever) while the 

 patient is convalescent, and possibly to all appearance fit 

 for duty, he should on no account be allowed to return to 

 work till he has had rest and good feeding for at least 

 a fortnight. 



Examination of the Blood for the Parasite. — Surgeon-Major 

 Ross recommends the examination of fresh blood without 

 drying or staining, and warns against trying to obtain too 

 thin a film by pressing the cover-slip on the slide, as there 

 is then a danger of causing some of the corpuscles con- 

 taining parasites to burst, so that they then appear free. 

 In squeezing the blood from the finger, the same effect 

 may be produced by the use of undue violence. The 

 blood must be taken from patients who have not had 

 quinine. 



Dr. P. Manson recommends the following procedure for 

 the examination of malarial blood (British Medical 

 Journal, December 1, 1894) : 



Cleanse very carefully with alcohol or ether several slips 

 and thin cover-glasses, and cover them up from the dust. 



