36 STUDIES IN ADVANCED PHYSIOLOGY. 



lodgment in the corpuscles. The corpuscle containing this 

 parasite loses its vital properties, is robbed of its coloring 

 matter, the haemoglobin, and so materially reduces the 

 efficiency of the blood to nourish the body. Two kinds 

 of parasites have been found which differ from one another 

 in the time required for producing new spores. In one 

 species each parasite produces a brood of new spores every 

 third day. In the second parasite the new brood arises 

 every fourth day. It is the formation of this new brood of 

 spores every third or fourth day which causes the malarial 

 paroxysm, probably because in the formation of the spores 

 some poisonous substance is eliminated. If, as it often 

 happens, the .patient houses in his blood two sets of these 

 parasites whose times of spore formation varies, the par- 

 oxysms vary accordingly, and so explain why the chill may 

 recur on successive days, then miss a day only to recur 

 again on the fourth day. We understand how the destruc- 

 tion of the red corpuscles of the blood by these infesting 

 parasites will produce the anaemia, so characteristic of 

 malarial fever. 



The germ of the only too prevalent typhoid fever we can 

 now produce in pure .cultures in the laboratory test tube. 

 We can see how it thrives and multiplies in decaying 

 organic matter. It can easily be observed what a healthy 

 medium sewage water is, and we can follow through all its 

 vicissitudes this agent of mortality. Bacteriology answers 

 satisfactorily the prevalence of consumption, the agent that 

 carries off more victims than probably any half dozen other 

 diseases combined. Nuttall, of Johns Hopkins Hospital, 

 in making quite a number of careful calculations found that 

 a patient only moderately advanced in the disease elimi- 

 nated from his body in the sputum during a short period of 

 twenty-four hours, from one and one-half, to four and one- 

 third billions of bacteria. These billions form part of the 

 dust which by the winds is spread broadcast and carries 

 infection to the first susceptible lung, or washed away by 

 the rains finally finds its way back through drinking water 



