482 GEORGE H. F. NUTTALL. 



" at last two of this species were persuaded to feed on a 

 patient with crescents. One of them was killed next 

 day ; no pigmented cells could be found. The second 

 was killed forty-eight hours after feeding ; numerous 

 pigmented cells were present. They were all small, 

 much smaller than epithelial cells, ovoid, about 

 7 ^ in the major axis, and each contained about 

 twenty granules of typical pigment, wliich were 

 often arranged circnmferentially, just as in the malarial 

 parasite." Though it is not stated in this publication 

 that he raised these mosquitoes from larvffi, reference to 

 Ross's previous paper (p. 178G) will show this to have 

 been a part of the method he employed. 



Experiments with Tertian Parasites. — "A lunidred or more grey or 

 ' barred-back ' mosquitoes, unfed or fed on healthy or crescent blood, 

 Lave been dissected witiiout finding the pigment cells. At last one was 

 observed feeding on a patient whose blood tliat morning had been seen 

 to contain numerous mild tertian parasites." Killed on the third 

 day, the insect contained many pigmented cells measuring 

 8 — 25 fi. (Ross subsequently discarded this experiment, as it was 

 possible that the insect which was not raised from the larva had become 

 infected with some other parasite.) 



May 21st, 1898, Experiments on Proteosoma. — Work- 

 ing in Calcutta, Ross observed the development of 

 Proteosoma in a species of Culex (subsequently 

 determined as C. fatigans, Wied.), the insects being 

 fed on the blood of infected crows, larks, and span-ows. 

 The parasites found in the external coat of the insects' 

 stomachs measured 6 fx after thirty hours, 60 fi after six 

 days. " Successive feeds by the same mosquito on the 

 same bird are followed by fresh crops of young coccidia. 

 . . . Similar pigmented cells" had been previously 

 observed in mosquitoes fed on human parasites. Ninety- 

 four per cent, of the mosquitoes fed on blood containing 

 mature Proteosoma became infected. 



September 24th, 1898, — Manson reported to the British 



