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



mosquitoes of this series germinal threads were found in the salivary 

 glands ; and those which fed, when examined later, gave the results 

 indicated in paragraph 9. 



On December 30 Dr. Rivenberg and myself examined these birds ; 

 three of them had Proteosoma, two in large numbers. 



On January 4 I examined them all except one which died on January 

 2 ; in this bird the heart's blood contained no Proteosomata, and the 

 organs were free from pigment. 



Five more of them had now Proteosoma ; in every instance the para- 

 sites were very numerous. On January 6 and 7 I again examined 

 them ; three more had Proteosoma, also in large numbers. 



On January 9 no more cases had developed ; but on January 18 one 

 of the birds had numerous Proteosomata. It was also ascertained that 

 many of these birds which previously had been found to be infected 

 had now recovered, whilst others showed but a few Proteosomata. 



Thus twelve out of twenty-two birds (54 per cent.) became infected. 

 This compares unfavourably with Ross's earlier results, as, in his pub- 

 lished series, twenty-two out of twenty-eight (79 per cent.) were 

 infected. But it is to be remembered that at the time this result was 

 obtained the germinal threads were found at the end of a week ; whilst 

 in December the development was much slower, and took at least twice 

 the time. It is much easier to keep mosquitoes alive during the first 

 week after feeding them than it is to keep them alive for any subse- 

 quent period ; moreover, in hot weather, such as Ross had worked in, 

 mosquitoes bite more readily. 



These results appear less unfavourable, if they are considered in 

 connection with observations on the normal proportion of wild, uncaged 

 birds, infected with Proteosoma at this season. Thus, earlier in the year, 

 Ross, out of 111 wild birds, found Proteosoma in fifteen, or 13*5 per 

 cent. ; whilst I found at this season only one out of thirty, or 3' 3 per 

 cent, affected with Proteosoma. 



It is possible that in the cold season the birds have a greater power 

 of resistance ; the validity of this conjecture is rendered more probable 

 by the short duration of the proteosomal attack in my infected birds. 

 Of the twelve, five died within the first week. In three of the survivors, 

 in which the Proteosomata had been very numerous, no parasites could 

 be found ten days after the commencement of the invasion ; in one in 

 which they were never numerous none could be found on the fifth day. 

 In the other three very few are now found, though at first they were 

 numerous. 



The recovery of these birds and the death of the mosquitoes fed on 

 them diminishes the chances of much future work on this line during 

 the time remaining to me here. 



11. Mention has been made of the differentiation of the eoccidia, 

 (previous to the formation of the germinal threads), according to the 



