214 
Development of Ascaris 
Davaine administered ripe eggs to rats and found that after twelve 
hours free, living larvae were to be found in the lower part of the small 
intestine. He also introduced ripe and unripe eggs in glass capsules 
closed with hnen into the alimentary canal of the dog and found that 
after the lapse of a certain period the ripe eggs had disappeared, whereas 
the unripe eggs remained. He concluded that hatching and develop¬ 
ment occurred in the alimentary canal of the definitive host. Grassi 
administered ripe eggs to himself and two months later found eggs 
in his stools. Calandruccio successfully infected a child of ten which 
had previously suffered from worms but had been relieved of these 
parasites by anthelmintics. Lutz fed an adult on ripe eggs and found 
evidence of the subsequent appearance of adult worms. Epstein’s 
work is unfortunately not available even in summary, but from the 
context of the references it is clear that he successfully infected man. 
Jammes and Martin allowed ripe eggs to hatch in artificial and natural 
solutions and found that hatching took place readily and en masse in 
0-8 % salt solution (which they consider to be an alkahne solution) at 37°— 
40° C. Martin (1913, cited by Wharton) finds that the embryos of the 
ascarids from the calf, pig, horse and dog, hatch best in alkahne solutions, 
and that when developed eggs are introduced into the ahmentary 
canal of an animal they pass through the stomach unaffected and only 
hatch after they have been subjected to the action of the alkahne 
juices of the intestine. Wharton states that direct infection can take 
place, but that the embryos must be “completely developed.” He does 
not give the period necessary to secure this complete development. 
In spite of the general acceptance of the hypothesis that infection 
takes place by the direct method there is a considerable bulk of evidence 
against it. 
Davaine administered three to four hundred ripe eggs to an ox, 
an animal which is stated to harbour Ascaris lumhricoides, and found 
that after four months no worms were present in the intestine. 
Leuckart (1867) fed a rabbit on ripe eggs and found no worms 
after ten days; a dog was also treated and was equally unresponsive 
after fourteen days. This very experienced helminthologist also fed 
a pig for three weeks on several thousand ripe eggs and did not find 
any worms on section. An experiment on man was arranged for in 
1857 but it is not clear that it was carried out. He also administered 
to a horse the eggs of Ascaris megalocephala, to a dog those of A. mar- 
ginata, to a cat those of A. mystax, with invariably negative results. 
Leuckart therefore maintained that the fife-history of A. lumhricoides 
