May 10,1924 
Ascaris Sensitization 
581 
From the results of these experiments, assuming for convenience of discussion 
that only one substance is involved, it is evident that the substance in aqueous 
extracts of Ascaris lumbricoides that causes the skin reaction in Ascaris-sensitive 
individuals is absent from the globulin fraction, present in the albumen fraction 
and present in the so-called protein-free filtrate, after the removal of the globulin 
and albumen fractions by precipitation with ammonium sulphate. It is weakened 
by oxidation with potassium permanganate so that it no longer produces a skin 
reaction in all Ascaris-sensitive persons. It is not volatile at temperatures 
between 20° and 100° C. It is thermolabile and is destroyed by exposure to a 
temperature of about 100° C. for less than an hour but may survive exposure to 
a temperature as high as 100° C. acting for a period of about 15 minutes. It is 
destroyed in the albumen fraction by digestion with pepsin. It is soluble in 
50 per cent alcohol. From the acidified protein-free filtrate it is wholly adsorbed 
by Lloyd’s reagent and wholly precipitated by Mayer’s solution. It is also 
wholly adsorbed from the acidified albumen fraction by Lloyd’s reagent but has 
not been recovered from the latter by subsequent treatment with weak alkali, a 
procedure which releases it from Lloyd’s reagent after adsorption from the 
so-called protein-free filtrate. The question whether it is of protein nature has 
not yet been answered by our investigations. 
In conclusion reference may be made to experiments which one of us has made 
with the body-cavity fluid and aqueous extracts of Ascaris lumbricoides , and 
extracts of the dried and powdered worms on various animals, by means of 
injections and local applications to the skin and eye. So far as concerns the 
local reactions produced in experimental animals which appear to be in a measure 
comparable to the urticarial reaction in human beings it is of interest to note that 
individuals sensitive to Ascaris lumbricoides may be found among both hogs 
(PI. 1) and sheep. Local reactions have not been observed in guinea pigs or 
rabbits, which are relatively resistant to the toxic effects of Ascaris substance 
when injected subcutaneously, intraperitoneally, or intravenously, whereas 
sheep and hogs, particularly the former, are highly susceptible to the toxic action 
of Ascaris substance when injected parenterally. Some dogs will react to dog 
ascarids brought in contact with the conjunctiva, and Weinberg and Julien 
( 6 , 7, 8) as already noted have shown that horses commonly give an ophthalmic 
reaction to the body-cavity fluid of the horse ascarid. 
Although the substances in Ascaris lumbricoides which cause local reactions in 
hogs and sheep may prove to be different from the substance that causes the local 
skin reaction in sensitive human subjects the fact that reactions very similar to 
that occurring in the human subject can be produced in lower animals as con¬ 
veniently available as hogs and sheep promises to be helpful in the investigation 
of the question of Ascaris sensitization and utilization of these experimental 
animals for studies on Ascaris sensitization may lead to results having an im¬ 
portant bearing on the general problem of sensitization of human beings to foreign 
substances. 
SUMMARY 
(1) Human beings are commonly sensitive to a substance contained in aqueous 
extracts of the nematode, Ascaris lumbricoides, an intestinal parasite of man 
and the pig. 
(2) Sensitive individuals exhibit a positive skin reaction when this substance 
is applied to a scratch on the skin, similar to that exhibited in cutaneous tests 
for so-called foreign-protein sensitization. 
(3) This substance is apparently absent from the meat of Ascaris-infested hogs 
and there is no reason to suppose that it is involved in cases of sensitization to pork. 
(4) Cutaneous tests on sensitive human subjects made with various fractions 
of an aqueous extract of Ascaris material separated by chemical and physical 
