XIII, B, 1 



Barber: The Transmission of Malaria 



15 



carrier. The arrangement of the pigment in the oocyst re- 

 sembled that of subtertian, although I have observed much varia- 

 bility in this character in undoubted subtertian oocysts. The 

 sinensis had been exposed to a relatively "potent" carrier, No. 

 1997, to be described later. It will be observed in this table 

 that infections were obtained with both benign tertian and cres- 

 cents in ludlowi and in var. indefinitus from brackish water. 



In Table VI all gamete carriers are classified according to 

 their number and the character of gamete harbored. Carriers 

 are arranged under three columns : Those under A were known 

 to harbor viable gametes at one feeding, at least; those under 

 B appeared in connection with positive feedings, but were never 

 the sole carriers under such circumstances — they must be clas- 

 sified as doubtful; those under C were always negative, never 

 appearing in connection with a positive feeding. 



Table VI. — Number and character of gamete carriers. 



Type of parasite. 



Crescents 



Benign tertian alone 



Crescents plus benign tertian 

 Quartan 



Total 



Percentage of grand total 



A, known 



to be pos 



itive. 



19 

 2 

 1 

 



22 

 27.2 



B, doubt- 

 ful. 



20 

 9 

 

 1 



30 

 37.0 



C, nega- 

 tive. 



18 

 7 

 1 

 3 



29 

 35. 



Tctal. 



57 

 18 

 2 

 4 



81 



The high percentages under B and C, of Table VI, are note- 

 worthy, since they indicate the large proportion of gamete car- 

 riers who apparently harbor nonviable gametes. 



In some cages the females were examined singly in test 

 tubes after the first feeding, and those known to have taken 

 blood were separated and given no further exposure to a car- 

 rier. In other cages, and possibly the larger number, insects 

 were exposed twice or more to the same or different carriers 

 and the "blooded" ones were not separated. In rossi, at least, 

 there was some indication of a greater mortality subsequently 

 among the "blooded" females, which were taken out immediately 

 after feeding. Further, examination of test cages seemed to 

 indicate clearly that few, if any, of the stronger females failed 

 to take blood when given two or three opportunities, especially 

 if the first feeding was done a day or more after emergence. 

 Apparently few, if any, of the weaker ones that failed to take 

 blood under these conditions lived long enough to be dissected. 

 Of the dissections in the controlled series 282 known to have 



