56 



NOTES ON A MALARIA-rARKYING MOSQUITO 



the red corpuscles are filled with pale protoplasm. In it are a 

 nnuiber of black specks or rods. These concentrate in the 

 cf^ntre, the, protoplasm arranf^inf,' itself around forminf,' a little 

 rosette. The walls of the blood vessels collapsing, the rosette 

 floats into the liquor sanguinis. Afterwards the rosette splits, 

 the black clump remaining and spores are set free. Some of 

 these penetrate red blood corpuscles, as pale specks. These 

 soon begin to throw out feelers in various directions, at the same 

 time wandering round the limits of the cell wall. They increase 

 in size by assimilating the ha-moglobin. P>y-and-bye appear 

 the characteristic specks of black pigment again. These little 

 detached feelers which wander about the blood fluid, and 

 penetrate corpuscles, appear to be of the nature of spermatozoa, 

 and propagate the disease. And the problem that struck 

 Manson was, how do they first find their way into the malarial 

 patient. In studying the matter, he concluded that the 

 mosquito was the most likely source. Not having the oppor- 

 tunity of working out the subject thorougly, he enunciated his 

 views and consulted with Dr. Ronald Ross, then about to proceed 

 to India. By a series of most patient and careful experiments, 

 he demonstrated some of the leading links in the process. 

 Other experimentors look up the subject and none more 

 enthusiastically than the Italian doctors, who have completed 

 the subject. On Manson's recent visit to Rome, Professor 

 Grassi showed bin) the pigmented vermicule in the inside of the 

 mosquito's stomach. It had got there by being fed on the blood 

 of a fever patient. Another specimen showed it penetrating the 

 stomach wall between two epithelial cells. In another it rested 

 in the interspace formed by the crossing of the muscular fibres. 

 Then it was shown as a warr. on the outer stomach wall. In the 

 inside of this were seen the little black rods having gone through 

 their cycle of development in the mosquito's body. ^Vhen the 

 walls of the capsule gave way these rods passed into the 

 mosquito's body. Endowed with ujoving and penetrating 

 powers, they travel along and easily penetrate the delicate skin 

 of the poison and salivary glands. Sections of these glands 

 were also shown him, actually containing large numbers of the 

 little germinal rods, this clearly tiacking step by step the whole 

 process from the blood of the patient up to the gland connected 

 with the proboscis of the mosquito. Numerous experiments 

 have been made on healthy Italian peasants, and recently Dr. 

 Manson's son offered himself as a subject. Pure Anopheles bred 

 from larva were sent to Rome and allowed to bite fever patients. 



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