7 86 THE POPULAR SCIENCE MONTHLY. 



tions of the soil have not varied for centuries ; how, then, can the 

 enormous increase of malaria be due to progressive alteration in the 

 chemical constitution of the soil itself ? Admit that malaria consists 

 in a living organism whose successive generations infect to an ever- 

 increasing extent the soil which contains it, and the explanation is 

 easy. 



Again, in regard to the malarious contents of the atmosphere. If 

 the malarious ferment (fermento malarico) were composed of gaseous 

 emanations from the soil, or of a chemical ferment formed in the soil 

 and raised into the air together with watery vapor, the malarious con- 

 tents of the atmosphere ought to reach their maximum in those hours 

 when the soil is most warmed by the sun's rays, and in which the 

 evaporation of the water it contains and the chemical processes occur- 

 ring within it are at their greatest intensity. But it is not so. The 

 malarious contents of the local atmosphere are less in the noonday 

 hours than at the beginning and close of the day that is, after sun- 

 rise and, above all, after sunset. Now, it is exactly at these two peri- 

 ods of the day that the difference between the temperature of the 

 l^wer strata of the atmosphere and the temperature of the surface of 

 the soil is greatest, and that the currents of air which ascend ver- 

 tically from the soil into the upper atmosphere are at their strong- 

 est. Admitting that the malaria is formed of solid particles of low 

 specific gravity (such as are the germs of the inferior vegetations), 

 we see at once how it ought to accumulate in the lower strata of the 

 atmosphere, especially in those two periods of the day. 



The tendency among investigators has always been to attribute this 

 specific poisoning of the air to a living organism which multiplies in 

 the soil; but, unfortunately, the "palustral prejudice," as Dr. Tom- 

 masi Crudeli calls it, has led them to examine only the lower organ- 

 isms which haunt marshes. In 1879 the author, in conjunction with 

 Dr. Klebs, discovered the cause of malaria in a " schizomyces bacilla- 

 ris," and recently Drs. Marchiafava and Celli have demonstrated that 

 this parasite attacks directly the globules of the blood and destroys 

 them after having determined in them a series of characteristic altera- 

 tions, which indicate quite certainly the existence of a malarious infec- 

 tion. " Many observations," says the author, " just completed in 

 Rome, would tend to demonstrate that this parasite does not inva- 

 riably assume the bacillary form described by Klebs and myself ; but 

 this purely morphological question need not concern the practical hy- 

 gienist. For him it is essential to know that he has to deal with a 

 living ferment which can flourish in soils the most diverse in compo- 

 sition, and without the presence of which neither marshes nor pools of 

 putrescent water are capable of producing malaria." 



Having incidentally shown that soils may contain this parasite in 

 an inert state and not produce malaria till the circumstances favorable 

 to its activity have arisen, Dr. Tommasi-Crudeli proceeds to demon- 



