62 PARASITES OF MAN. 
also employed eggs, containing the embryos, in a similar set of 
experiments on rats and dogs. He also introduced them into 
the stomach of a cow, in linen-covered flasks. Some embryos 
escaped their shells, but nothing further transpired. Leuckart’s 
experiments on insects also failed. Numerous worm-feedings 
with allied species of Ascaris have given similar general results 
at the hands of Leuckart, Davaine, Verloren, Unterberger, and 
myself. Heller says that the first moult of the larva occurs 
within the egg itself; a second ecdysis taking place before the 
worm arrives at sexual maturity. 
Remarks.—There is every reason to believe that infection com- 
monly occurs by persons carelessly drinking water into which 
the eggs of the worm have been accidentally or otherwise intro- 
duced, and within which medium the embryos have been 
hatched during warm weather. Pigs being infested by the same 
worm, the water from streams or ponds in the neighbourhood 
of pigstyes becomes a dangerous source of infection when 
employed fordomestic purposes. Local endemics are traceable to 
this source. Careful filtration of water containing larvee, before 
use, would probably of itself be an amply sufficient safeguard 
against infection. The determination of the identity of 
Dujardin’s so-called Ascaris suilla of the hog with A. lumbricoides 
of man is due to Schneider. The large lumbricoid worm of the 
horse (A. megalocephala) is an entirely distinct species. In 
consequence of the tendency of lumbricoid worms to wander, 
they frequently give rise to grave symptoms and severe suffer- 
ing to the human bearer; and they occasionally cause death 
by perforating the walls of the intestine. This fact implies the 
possession of great muscular strength. In the year 1863 Mr. 
Hughes read a paper to the Birmingham Natural History Associ- 
ation, in which he described the remarkable contractile powers 
of Ascaris luwnbricoides. Mr. Hughes and Mr. C. J. Bracey, 
(House Surgeon to the General Hospital,) acting together, placed 
living specimens of the worms in water, raised to a temperature 
of about 100° Fahrenheit. This had the effect of keeping the 
parasites alive for several hours, during which time they 
displayed remarkably vigorous movements, their bodies con- 
tracting violently. 
Literature.—Standard Works. See also Heller (Joc. cit., ‘‘ Midland 
Naturalist,” Vol. II., p.8.) In connection with sanitary questions, 
it may be useful to refer to my memoir “‘ On Sewage and Parasites, 
especially in relation to the dispersion and vitality of the germs 
of Entozoa,” in the Medical Times and Gazette for Feb. 25th, 
1871, p. 215, et seq. 
41.—Ascaris mystax, Rudolphi. 
Syn.— Ascaris alata, Bellingham; A. cati, Schrank; A. teres felis, 
Goeze. 
Larvee.—As intra-ovular embryos, the early stages are developed 
whilst the eggs are still within the body of the parent female 
worm. After hatching, and a subsequent residence in the outer 
world, so to say, their passive transference to the ultimate host 
is attended with rapid growth and a final ecdysis.. Leuckart 
has traced these stages of growth in the cat, in whose stomach 
specimens of the larvee were found, measuring only ;, of an 
inch. The final skin is cast when the larve are about } of an 
inch long. From Hering’s observations, it would seem probable 
that a period of three weeks is amply sufficient for the produc- 
