60 
was noticed in the patient during the period of observation, which 
continued until August 28. 
J. 0 ., age 18, Mexican .—He was taken to Yera Cruz August 13 
and placed in the mosquito-proof ward. On August 28, at 9.30 a. m., 
he was bitten by four mosquitoes, two of which had fed sixteen days 
previously, at 4 p. m., on A. L., a fatal case of yellow fever, forty 
hours after the onset of the disease, and the other two had fed fif¬ 
teen days previously, at 10.30 a. m., on the same case fifty-eight hours 
after the onset of the disease. The patient remained perfectly well 
throughout the following month while under observation in the 
screened room. 
M. R., age 21, Mexican .-—He was brought to Vera Cruz August 28 
and kept in the screened ward. On September 1, at 6.30 p. m., he 
was bitten by two mosquitoes which had fed nineteen days before, at 
10.30 a. m., on A. L., a fatal case of yellow fever, fifty-eight hours 
after the onset of the disease. The patient continued in his usual 
health during Sepember 2 and 3. On September 4, at 2 p. m., on 
going into the ward the patient was found wrapped in his blanket 
and said he felt chilly and complained of slight temporal headache. 
There was no elevation of temperature. 
The next case succeeded: 
Yellow Fever Produced by the Bites of Mosquitoes. 
Marcos Cruz (case XLII), age 21, born in Perote, a mountain 
town free from yellow fever, where he has always lived. States that 
he never had fever of any kind. He was physically sound on exami¬ 
nation, and brought to Yera Cruz, where lie was immediately placed 
in a mosquito-proof room and kept under observation for fourteen 
days, when he was bitten by 11 mosquitoes, as follows: 
On September 11, at 9 o’clock a. m., 3 mosquitoes which had fed 
fifteen days previously, at 9.30 a. m., upon Trinidad Martinez, a fatal 
case, fifty-one hours after the onset. At the same time, 3 other mos¬ 
quitoes, which had fed fourteen days previously, at 2.30 p. m., upon 
Hipolito Yasquez, a fatal case, sixty-nine hours after the onset of the 
disease. At 2 p. m. of the same day he was bitten by 2 more mosqui¬ 
toes, which had fed fourteen days previously, at 2.30 p. m., on Hipo¬ 
lito Yasquez, sixty-nine hours after the onset. 
The next day, September 12, at 2.30 p. m., he was bitten by 3 
mosquitoes, 2 of which had fed fifteen days previously, at 2.30 p. m., 
on Hipolito Yasquez, sixty-nine hours after the onset of the disease, 
and the other had fed sixteen days previously, at 9.30 a. m., on Trini¬ 
dad Martinez, fifty-one hours after the onset of his disease. 
On September 12 and 13 the patient had no symptoms, and his 
temperature remained normal. 
