75 



from one to three days, and a large Berkefeld allowed pyocyaneus 

 and prodigiosus to pass in seven days. 



Wherry a states that the bacillus producing pneumonia in guinea 

 pigs (0.5 micron wide and 0.7 micron in length) passed the small 

 Berkefeld No. 5, but was not found in the filtrate from the thicker 

 walled Berkefeld No. 8, nor in the filtrate from the Chamberland F. 

 It, however, grew through the walls of all three. 



FOMITES. 



While we made no experiments directly designed to determine the 

 part played by fomites in transmitting the infection of yellow fever, 

 still our work strongly bears on this point, and we can fully corrobo- 

 rate the conclusions of Reed and Carroll that fomites or inanimate 

 objects are not dangerous in this respect. 



Nonimmunes whom we kept for weeks under observation in our ' 

 mosquito-proof rooms slept on the same beds, used the same clothing, 

 washed from the same bowl, ate the same food, drank the same water, 

 and breathed the same air as those sick with yellow fever; neverthe- 

 less they remained free of all "fever except that which was purposely 

 given them by mosquito bites or blood inoculations. 



As these experiments Avere done in the summer time at Vera Cruz, a 

 badly infected city where the disease prevailed at the time in epidemic 

 form, it removes some of the objections which were made at the time 

 to the work of the Army Commission, which for the most part was 

 done during the winter months in an otherwise healthful locality — 

 Camp Lazear. 



THE PILTEATION OP MALAEIAL BLOOD. 



The filtration experiments with malaria were undertaken with the 

 hope that they would throw light upon yellow fever, which bears so 

 many analogies to malaria. Both diseases are transmitted by mos- 

 quitoes, and it is therefore natural to suppose that yellow fever is due 

 to an animal parasite, perhaps similar to the well-known plasmodium 

 of Laveran. However, as the one disease is filterable and the other 

 is not; and as the parasite of the one is visible and the other can not 

 be seen with the highest powers of the microscope at present at our 

 command, either in the mosquito or in man; and as the one produces 

 an immunity and the other does not, we find the analogy is not after 

 all so very striking and that it does not seem helpful in solving our 

 problem. 



The malarial rosette breaks and liberates spores (merozoites) which 

 are exceedingly minute, and in order to carry out the analogy in an 



" Journ. med. research, vol. 8, 1902, p. 322. 



