﻿400 ^^6 Philippine Journal of Science is" 



sites an opportunity to develop sporozoites and infect the salivary- 

 glands. For this purpose, mosquitoes which had fed on infected 

 blood were kept alive for from twelve to eighteen days before 

 dissection. Both the mid-gut and the salivary glands were 

 then dissected. In removing the salivary glands from the mos- 

 quito, the methods described by Stephens and Christophers 

 (1906) were employed. The legs and wings of the mosquito, 

 the abdomen of which had already been removed for the dis- 

 section of the mid-gut, are cut off with a sharp needle, the cuticle 

 at the prothorax is torn with the needle, the slide is placed 

 over a black background, the thorax is held by one dissecting 

 needle, while gentle traction is exerted on the head with a second 

 needle. This will, if properly done, draw out the salivary glands 

 from the thorax attached to the head. They are then cut off 

 from the head with a sharp needle, a cover glass is placed over 

 them, and they are examined with the high dry and then with 

 the oil-immersion objective of the compound microscope for the 

 presence of sporozoites. In case of failure to remove the salivary 

 glands by this method, they can still be found by carefully 

 teasing apart the tissues of the anterior ventral part of the 

 thorax. 



The mid-guts when found infected were preserved. In most 

 cases the entire mid-gut was placed in 0.85 per cent sodium 

 chloride solution containing 10 per cent formalin. In a few 

 cases Schaudinn's sublimate alcohol mixture was used as a 

 fixative, after which the organs were preserved in 70 per cent 

 alcohol. Smears were made of the infected salivary glands, 

 which were stained by Giemsa's stain, by sliding off the cover 

 glass. Sections were not made for diagnosis, as the dissection 

 method is much quicker and simpler; but in a few cases sections 

 were cut for permanent preparations. 



III. EXPERIMENTS 



There is a notable lack of detail in the reports of most authors 

 on their experiments in infecting mosquitoes with malarial par- 

 asites. For this reason, and because our experiments have 

 been more extensive and more quantitatively accurate that those 

 hitherto performed, it has seemed desirable to give a detailed 

 account of our investigation. In order first to present a com- 

 prehensive view of our experiments in a form that will economize 

 space and at the same time facilitate a comparison of the data 

 and the results, their essential facts are tabulated in Table II. 



