the worm escapes from the siirroimding' cast skin. While water is 
more or less injurious to the egg and the first stage, the infecting 
‘‘encysted" stage exists well in this medium, and Looss (1897) suc- 
ceeded in keeping these worms alive for thirty days in water. Upon 
drying up the larva? die, so that the view that the worms exist in dust 
and are carried around in the air, thus leading to infection, is not well 
founded (see p. 30). 
DEVELOPMENT INSIDE THE BODY. 
Upon being swallowed these young worms undergo further ecdyses, 
changing their internal organization at the same time. We may 
recognize, with Looss, a third stage, without buccal capsule (fig. 32); 
a fourth stage, with a provisional buccal capsule (fig. 35); finally, a 
fifth stage, with the definite buccal capsule, corresponding to the adult 
form. 
Third stage {vnthoiit huccal cajysule^ fig. 32). — During their free life 
the larva? mav attain 0.65 to 0.7 mm. in length bv 25 to 27 \-i in diam- 
Figs. 38-39. — DeTelopraeut of definite buccal capsule (38, on twelfth day after infection; 39, one 
or two days later): d. b. c., definite buccal capsule; e. g. d., dorsal esophageal gland: m. m., margin 
of definite mouth ; p, papillse on head ; p. b. c. d., p. b. c. t\, dorsal and ventral primordia of the 
definite buccal capsule ; p. t., primordium of ventral tooth ; t., ventral tooth ; the new cuticle can 
be distinguished under the old. X 190. (After Looss, 1897, p. 923, figs. 7-8.) 
eter (at the end of the esophagus). The esophagus is 160 /.i long, and 
its three divisions mav still be distinguished. The intestine is com- 
posed of about 15 rows of two cells each. 
^ Fifteen hours after infection of dogs the worms have passed below 
the stomach. They now begin to feed, but their growth is compara- 
tively slow. After about five days they begin to show signs of a 
third ecdvsis, which continues until about the seventh day. During 
this period important changes take place, especially at the anterior 
end, and result in the formation of the provisional buccal capsule. 
Fourth stage {irith jyrovisional huccal capsule^ fig. 35). — This is 
the fourth larval stage, namely, the stage after the third ecdysis. The 
worms have not increased notably in length, but certain organs are 
advanced in development, and the esophagus no longer shows its for- 
mer three divisions. The worms measure about 0.66 mm. long by 25 p 
in diameter, the latter being nearly uniform for a greater part of the 
