BY W. R. COLLEDGE. 67 



Carefully protected from other contaminating influences, they 

 were sent to London, and there permitted to bite young ]\Ianson. 

 There in the English climate malarial fever was developed, and 

 in his blood was seen the black pigmented and crescentic forms 

 so characteristic of the disease. Italian doctors who have 

 studied the subject, and whose opinion must carry weight, give 

 their deliberate conviction that the mosquito is the only source 

 of human infection. They believe that it does not originate 

 from residence in a malarial district. It cannot be received 

 from drinking impure water, neither is it spread from personal 

 contact with a malarial patient, but solely by the bite of this 

 peculiar species of mosquito. r)eing a blood disease, it requires 

 a blood channel for its propagation, and this is found in this 

 little insect. Break down the bridge of the mosquito and 

 malaria will be stamped out. " A consummation devoutly to 

 be wished." The scientists may be too sweeping in the asser- 

 tion that the disease only originates in this way from a fever 

 patient. I do not thiak it has been proved that malaria does 

 not exist in any other living creature ; if it does, that might be 

 the original source. The question of it is only derived from a 

 diseased patient, Where did the first mosquito receive it ? This 

 opens up a wide speculative field, but as the first mosquitoes 

 are found in the Tertiary rocks of the Lower White River, 

 Colorado, long before the beginning of human history, it is 

 evident that the answer would be difficult to find. The practical 

 fact that this is the main source of contagion now is too clear to 

 admit of doubt. 



Another fact of great value to the world has recently come 

 to light in these researches. Medical men in tropical countries 

 have a great many patients who are seriously ill, but yet there 

 are either few peculiar symptoms, or they are of such a general 

 character that the doctor cannot put them down to any special 

 disease. A large number of these cases are of malarial origin, 

 which can be determined by a simple examination of the blood. 

 A few minutes with a good microscope now settles the question, 

 which formerly worried for months earnest medical practitioners. 



I have another slide, Fig. 22, which I am sure will interest 

 Mr. Pound. He knows a good deal about cattle ticks, and our 

 pastoralists have been sore sufferers from their ravages, I do 

 not know whether they will derive any consolation from the 

 fact that they are not the only sufferers, but that mosquitoes 

 likewise suffer from ticks. And the cattle tick to them is but a 

 pigmy. Comparatively speaking, these ticks would be about the 



