MEASLES. 419 



short duration. The course of events in the disease 

 might be explained by supposing that immunity is produced 

 in the course of the disease, but that it does not last 

 until all the spirilla have been destroyed. With the dis- 

 appearance of the immunity the organisms reappear in the 

 blood, the relapse being, however, of shorter duration and 

 less severe than the first attack. This is repeated till the 

 immunity lasts long enough to allow all the organisms to 

 be killed. On these points, however, further information is 

 still necessary. Any antimicrobic power which the serum 

 may possess after the crisis has not yet been demonstrated. 

 It is further to be noted that relapsing fever is unique 

 amongst diseases affecting the human subject, in respect 

 of the enormous numbers of organisms which can be 

 observed in the circulating blood during life. 



MEASLES. 



Though measles is a disease of such frequent occurrence, 

 and though its course and infectiveness suggest the presence 

 of a causal micro-organism, we cannot be said to know 

 definitely anything of the nature of the latter. Two 

 organisms have been stated to be found associated with 

 the disease one said to be a protozoon, the other a 

 bacillus. With regard to the former, Doehle (in 1892) 

 found in the plasma and red blood-corpuscles, on the first 

 or second day of the disease, more or less numerous round 

 motile organisms J-i // in diameter, with a clear periphery 

 and darker central part. They could be stained by Loffler's 

 methylene-blue. They sometimes showed 2-4 nuclei and 

 one or two flagella. Sometimes they were larger, being 

 2-2 J fji in diameter, with a relatively large nucleus which 

 contained i to 8 smaller curved bodies. L. Pfeiffer and 

 also Behla have described similar organisms. The latter 

 observed darkly-stained bodies in the nasal mucous mem- 

 brane, which he looked on as spores. As in the case of 

 other alleged protozoa, these organisms have not been 



