﻿530 BANKS. 



INOCULATION OF MOSQUITOES. 



At the beginning of the work numbers of mosquitoes were fed upon 

 blood from persons negative for the malarial parasite, and I also allowed 

 several of the insects to bite me. The mosquitoes were dissected at inter- 

 vals of from eighteen hours to several days after biting, for the purpose 

 of becoming perfectly familiar with the appearance of the internal organs, 

 including the stomach, the thoracic cavity, muscles, and the salivary glands 

 under normal conditions. After this had been done and the technique 

 thoroughly outlined, patients were selected whose blood had, upon exam- 

 ination, shown the greatest number of parasites of the aestivo-autumnal 

 type, which was chosen because of its great prevalence among the troops 

 and the presence in the hospital of men who at the time were well infected 

 by the crescent forms. The tubes used to carry on the work were prepared 

 so that some contained a single insect, others held six and others twelve ; 

 those with but one being kept for voluntary cases who would submit to 

 being bitten by the infected mosquitoes. The others contained insects 

 which were to be allowed to bite malarial persons and then were to be 

 placed in alcohol or dissected at various periods in the development of the 

 parasites. 



Dissection of mosquitoes. — Six hours after the mosquitoes had first 

 bitten the patient, the insects were dissected and, from the blood within 

 the ventral reservoir, smears were made upon slides, fixed and stained 

 with Wright's stain after the usual method. At first some difficulty was 

 experienced in obtaining a satisfactory adhesion of this blood to the 

 slides. It was found that by either heating alone, or fixing with absolute 

 alcohol and ether alone, the blood would largely be removed when it 

 came to staining the slide. Finally, a combination of the two processes 

 was used, heating first and treating with alcohol-ether afterwards being 

 resorted to. 



The crescents and ovoids were demonstrated in the blood obtained as 

 above, but, unfortunately, mosquitoes in this stage were not placed in 

 alcohol, so that no specimens of this part of the phenomenon were pre- 

 served except on the smears of blood taken from the stomachs of the 

 insects. 



Mosquitoes were dissected daily from the time of "the first ingestion 

 of blood, but nothing of interest was noted in the unstained tissues up 

 to the day when the swellings in the gastric mucosa indicated the probable 

 growth of the oocysts. The fourth and fifth days' dissection demonstrated 

 a considerable enlargement of the oocysts, which attained a diameter of 

 from 30 to 60 p. On the sixth and seventh days they were for the greater 

 part found as collapsed bodies on the ccelular surface of the stomach wall. 



Sectioning of mosquitoes. — Further tracing of the parasites in any 

 but sectioned specimens was impracticable. Mosquitoes were therefore 

 put into alcohol and sent to Manila for sectioning, so that all stages of the 



