F. H. Stewart 
215 
would be found to be completed by an alternation of hosts. He sup¬ 
ported this opinion by the facts known with regard to (1) acm 
which is found as an encysted larva in Leuciscus alburnus and in the 
adult form in the pike, and (2) a larval Ascaris found encysted in the 
muscles of the mole which when administered to the buzzard {Falco 
huteo) continues to develop although it does not yet become adult. 
Leuckart considered that Davaine’s rat experiment, if correctly 
described, did not point to the direct development of the worm but 
to the fact that the rat was an intermediate host. He pointed out 
the ease with which the larvae hberated in the faeces of the rat would 
be conveyed to the intestine of the definitive host,—man. He 
attempted to confirm the experiment but employed a mouse in place 
of a rat, and found that the eggs were passed unaltered in the faeces 
of the mouse. He therefore abandoned this fine of research. He 
attempted to find the intermediate host among invertebrate animals 
experimenting with a number of insects, snails and earth-worms but 
without success. 
Von Linstow (1886) suggested that Julus guttulatus might be the 
intermediate host. 
The Author’s Observations. 
Ascariasis both in man and the pig is of extraordinary frequency 
in the colony of Hong Kong and in South China generally, the author 
therefore while stationed in this colony had an unusual opportunity 
of studying the subject. He commenced experiments in the spring 
of 1915. 
(1) Two yoimg pigs were obtained aged two months. The faeces 
of both were examined and found to be free from Ascaris eggs. 
Pig A was fed throughout the course of the experiment on tinned 
milk- and rice flour. Large quantities of ripe eggs from the Ascaris 
of the pig were administered to it on thirteen occasions between the 
20. ix. and 6. x., 1915. The age of the eggs employed varied from 
26 to 64 days and they invariably contained well developed and motile 
embryos. They had been incubated at 25°-30° C. in a damp atmo¬ 
sphere. The eggs were administered under varying conditions, after 
food and after twelve hours’ starvation, with and without the addition 
of bicarbonate of soda. The total number of eggs used must have 
greatly exceeded several thousand. This pig was killed 15. xii., 1915. 
One small Ascaris only was found in its intestine. 
