86 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 134 
were present in 66 percent of the cockroaches after 3 days, and in 
33 percent after 10 days. 
Periplaneta americana, South Africa (Porter, 1918): See com- 
ments under B. ortentalis. U.S.A. (Hegner, 1928): T. hominis, in- 
gested with human feces, was destroyed in the crop of the insect 
within 2 to 54 hours. No flagellates were found in the insects after 
2 days; very few survived until they reached the intestine. 
Family HEXAMITIDAE 
Giardia intestinalis (Lambl) 
Synonymy.—Guiardia lamblia; Lamblia intestinalis. 
Disease.—Although a majority of persons harboring G. intestinalis 
are asymptomatic, others have a persistent diarrhea. 
Experimental vectors—Blatta orientalis, South Africa (Porter, 
1918): The cockroaches were fed on human excrement that con- 
tained G. intestinalis. Cysts of this protozoan passed unchanged 
through the cockroaches and were recovered from their feces. These 
same cysts, when fed to rats, caused diarrhea. 
Blattella germanica, Brazil (Pessoa and Correa, 1927): Adults 
and nymphs were fed cysts of G. imtestinalis. These cysts were re- 
covered from feces up to 5 days after feeding. The greatest number 
of living cysts was found 48 hours after feeding. 
Eurycotis floridana, U.S.A. (Young, 1937) : Experiments showed 
that cysts fed to adults and nymphs reached the insects’ colons within 
2 hours. 
Leucophaea maderae, Brazil (Pessoa and Correa, 1927): Nymphs 
only of this species were used. Thirty-four living cysts were found in 
the feces up to 7 days after feeding. 
Periplaneta americana, South Africa (Porter, 1918): See com- 
ments following B. orientalis. Gold Coast Colony (Macfie, 1922): 
In two experiments, cysts of G. intestinalis, fed in human feces, 
passed through the cockroaches’ intestines apparently unharmed and 
unchanged. Brazil (Pessoa and Correa, 1927): Live cysts were 
found in the feces up to 5 days after feeding. Two specimens regurgi- 
tated a milky fluid, up to one-half hour after feeding, that contained 
live cysts. U.S.A. (Young, 1937) : See comments under E. floridana. 
Cysts remained in the insects’ intestines as long as 12 days, but the 
viability of these cysts was not tested. 
Periplaneta brunnea, U.S.A. (Young, 1937): See comments under 
E. floridana and after Young under P. americana, 
Cockroaches, Venezuela (Tejera, 1926): A group of 30 cock- 
