444 Dr. C. W. Daniels. On Transmission of 



Of each of these series Major Ross dissected specimens, and demon- 

 strated in them the same bodies that he had already shown me in 

 prepared specimens. He pointed out that in the older mosquitoes it 

 was possible to predict from an examination of the fluid obtained on 

 cutting the thorax the nature of the contents both of the " coccidia " 

 (the term employed by Ross)* in the stomach, and of the cells of the 

 veneno-salivary glands. 



These points I readily observed. 



4. Of the mosquitoes referred to I day by day examined those 

 which died, and others which I killed. In these I was able to repeat 

 the observations and, in insects belonging to the earlier series, to trace 

 the changes in the size and in the nature of the contents of the 

 " coccidia." 



I also examined a large number of mosquitoes caught about the 

 laboratory, and others which had been raised from larvse. In none of 

 these did I find either " coccidia " in the stomach wall, germinal threads 

 in the body fluids, or germinal threads in the cells in the salivary 

 glands ; nor did I find " black spores " (Ross). 



5. Major Ross informed me that his published results were based on 

 observations made in the hot season, when the temperature was 80 F., 

 or over; and that now, as it was the cool season, I should find the 

 changes progress more slowly, although the sequence of events was the 

 same. My observations on the mosquitoes fed on December 20 and 

 December 15 showed that this was the case. Major Ross also informed 

 me that, with the lowered temperature, mosquitoes fed less readily, 

 and that more difficulty was experienced in rearing them to a spore- 

 bearing age. 



These difficulties the use of the incubator was only partially success- 

 ful in overcoming. 



6. On the evening of January 1, following exactly in Major Ross's 

 lines, I commenced a repetition of his main experiment : 



A large number of grey mosquitoes, reared from larvae, were 

 released in two mosquito nets. 



In net No. 1 four birds were placed. On December 31 I had 

 already found Proteosomata in large numbers in three of these birds, 

 and in the fourth in moderate numbers. 



In net No. 2 two birds, in whose blood no Proteosomata had been 

 found, were placed. These two birds died two and three weeks later ; 

 on dissection no black pigment was found in their organs. Repeated 

 examinations of their blood had failed to discover Proteosomata. 



On January 2 none of the mosquitoes had fed, and on January 3 



only two in net No. 1 and eight in net No. 2. On January 4, 



which was a warm night with a minimum temperature of 59'2 F., 



sixty-three mosquitoes were found in the morning gorged with blood 



* See note by the Malaria Committee appended to this Report. 



