1896. SOME NEW BOOKS. 333 



ture. The temperature of Zanzibar is one of the most uniform in the 

 world ; the annual range of temperature is about 70° Fahr,, but the 

 town reeks with malaria. On the other hand, on parts of the Masai 

 plateaux the daily range of temperature may be 70°, but malaria, in 

 some of these places, is unknown. 



The author's criticisms of the organic theory are not always up 

 to date. He shows a full knowledge of the literature of his 

 subject up to 1885, but not for later years. His arguments are often 

 fatal to the organic theory of 1886, while they do not shake that theory 

 as we know it in i8g6. It is within the last six years that the 

 haematozoic theory has been proved. Pages are devoted to the 

 refutation of the suggestions of Salisbury, Klebs, and Tommasi- 

 Crudeli, which have now only an historic interest, whereas the dis- 

 coveries of the last few years are not considered. The author is 

 clearly a patient and conscientious worker, who mastered the 

 whole subject as far as was possible at the time of his three years' 

 research upon it. Had the book been published immediately after his 

 return it would have been of great value ; but since then the author 

 does not seem to have had his former opportunities or access to 

 medical literature. Hence the book is several years out of date, and 

 its main value depends on its account of the past history and present 

 distribution of the disease. 



Dr. Manson's Goulstonian lectures treat malaria from an 

 altogether different point of view. He accepts the parasitic theory 

 as fully established. He tells us that "there cannot any longer 

 be the slightest doubt that it [Laveran's parasite] is the germ of 

 malaria ; there cannot any longer be the slightest doubt that incidents 

 connected with its multiplication in the human body are the causes of 

 the clinical phenomena of malaria. These things are now abundantly 

 proved, and are accepted by all who have taken the trouble to make 

 themselves personally acquainted with the facts and the parasite." 

 Starting from this premise, his faith in which we do not think at all 

 excessive. Dr. Manson endeavours to trace the life-history of the 

 malarial haematozoon during the stages which it must pass through 

 outside the human body. It was known that when malarially-infected 

 blood corpuscles were drawn from the body some of the malarial 

 spherules broke up into free-swimming flagellated bodies. The ex- 

 planation given of these flagellated bodies by most workers is that they 

 are degenerate haematozoa(or plasmodia, as they are generally called in 

 medical literature). This is the view adopted by Blanchard, Labbe, 

 Marchiafava, and Begname, but opposed by Laveran, Nannaberg, 

 Danilewsky, and others. Dr. Manson now explains this flagellated 

 stage as one adopted by the haematozoon when it escapes from a body 

 in order to secure its proper distribution. He considers that it is the 

 first extra-corporeal stage in development, and, as it cannot be pro- 

 duced in the host, he concludes that one part of the normal develop- 

 ment of the haematozoon is outside the body of the host. He suggests 

 that the mosquito is the agent which effects the liberation of the 

 parasite. He shows that this is probable from the facts of the dis- 

 tribution of the disease, and from the interesting analogy between 

 filaria and the malarial parasite. This evidence is not conclusive, but 

 some experiments made in India by Surgeon-Major Ross at Dr. 

 Manson's suggestion have certainly made one important step towards 

 proving the theory, for it has been demonstrated that if a mosquito 

 sucks in blood containing the malarial spherules, that these develop 

 in the insect into the flagellated bodies. 



Considering the enormous influence of malaria in all tropical 



