19, 3 Maxwell: Filariasis in China 265 
the disease about thirteen and twelve years previously; at least 
their attacks of fever began about that time. Although they 
had continued to live cooped up in this — no other member 
of the family had been infected. 
TABLE 5.—Showing irregular incidence of infection of one family by filariz. 
Age. Condition. 
Dead; had slight elephantia- 
athe os Se chee aes sis of | eg. 
ta | np cate ep OUR ERD ret OM, keen eee ee, 60 | Uninfected. 
Rates site dene x Lich wad encn ates “8 18 | Bought. Nosignof disease. 
LFS i ty A RNA SR le, RAD Je ben rue eee 87 | Uninfected. 
DO oc et ee eee 34 Do. 
iscsi ccd Sosrtetsnekl dud Sa ki ie 31 | Infected. 
hs Renee Sere pene CON aay Ty oO pier NT epee ek Tenet 29 Do. 
DO ane cass cco e ee ean ce ee ee 26 | Uninfected. 
rane eo 
Three years ago one of the infected individuals went to 
live in a separate house with his aunt and cousin. Although 
mosquitoes infected with filarie have been found by me in this 
house, and there is nothing to prevent the members of the 
household being freely bitten, yet this aunt, aged 50, and cousin, 
aged 13, remain uninfected. The other infected individual 
married two years ago, and his blood literally swarms with 
filarize, yet his wife at the present time shows no sign of disease. 
How are these facts to be explained? It may be declared 
that in order to bring about a successful infection the mosquito 
bite must be in a region richly supplied with lymphatics and 
that probably this has not been the case in these persons. Both 
of the infected brothers are, otherwise, strong and healthy, and 
they were in good health when the attacks began. This tends 
to negative any theory that rests on the premise of lowered 
vitality as the cause that makes successful infection take place. 
The probability that a single individual can be infected more 
than once, and that many mature worms may be found in the 
same subject, seems on the other hand to indicate that, in some 
instances at least, infection is not a work of great difficulty. 
It is very probable that many people are bitten by the filaria- 
infected mosquito, with the result that the worm passes into 
their tissues, but it does not follow that embryos appear in the 
blood of such patients. For the appearance of these, it is 
necessary that the female worm should be present and should 
have been fertilized by the male. 
Let us suppose that the male fails to find the female. 
Possibly they die and are absorbed without giving trouble. 
