578 
Journal of Agricultural Research v 0 i. xxvm, No. 6 
The horse Ascaris appears to be more powerful in its effects than the human 
Ascaris, judging from the fact that more severe symptoms have been commonly 
reported among persons sensitive to the former than among those sensitive to 
the latter, but this may be related to the fact that the horse Ascaris has been 
in general more intensively worked with by zoologists than the human Ascaris, 
so that exposure has commonly been greater in the case of the former. Indi¬ 
viduals may be sensitive to both species, as in the case of Goldschmidt, or sensi¬ 
tive to one and not to the other, as in the case of Bastian, in whom the horse 
Ascaris would cause severe asthmatic attacks but upon whom the human Ascaris 
had no effect. Whether an individual may be sensitive to the human Ascaris 
and not to the horse Ascaris has not been clearly established although we have 
been informed that one zoologist who was susceptible to the effects of the human 
Ascaris, experienced no discomfort after this susceptibility had been noticed 
in handling a large number of living specimens of the horse Ascaris. As noted 
by both Bastian and Goldschmidt the severity of the symptoms if originally 
mild may increase with repeated exposures, and in some cases the symptoms 
have become so severe as to force susceptible individuals to abandon further 
scientific work involving the use of the offending parasites. 
The investigations that we have recently undertaken are the outcome of the 
discovery by one of us of his susceptibility to the toxic action of Ascaris lumbri - 
coides on contact with the worm, (4) a discovery made about five years ago. 
At that time following the appearance of eye symptoms (irritation, lacrimation, 
and swelling of the eyelids) a cutaneous scratch test was made with some of the 
body fluid of the parasite, the results of which were positive. Later on one 
occasion the same individual experienced a severe general reaction as the result 
of a drop of Ascaris fluid falling unnoticed on a very small but fresh abrasion of 
the skin. This attack was characterized not only by a local wheal with surround¬ 
ing erythema, but by extensive lymphatic involvement, which was evidenced 
by red streaks extending up the arm to the shoulder, swelling of the face, urti¬ 
carial wheals over the entire body, very rapid heart, discomfort in the throat, 
and a sensation of warmth and breathlessness. The more alarming symptoms 
disappeared within a couple of hours, but the face and eyelids were still swollen 
the following day and the arm in the region of the local reaction was still swollen 
and reddened. More or less discomfort and various unpleasant symptoms 
have since been experienced under circumstances that involved direct or indirect 
exposure to Ascaris, although care has been taken to minimize the chances of 
close contact with the parasite so far as is possible in a parasitological laboratory. 
In our recent investigations, which are still unfinished and of which a complete 
report can not now be given, certain observations have been made which appear 
to be of sufficient interest to warrant the presentation of a brief progress report 
About 20 persons, all white adults, have been tested for sensitiveness to Ascaris 
lumbricoides by means of a cutaneous scratch test. Among these there were 4 
reactors, all of whom had been more or less exposed during periods of 5 to 25 
years to contact with Ascaris. None of the reactors had a definite history of 
Ascaris infestation. Among the nonreactors were several who gave a history of 
having passed ascarids during childhood, and there were also several nonreactors 
who had at various times been considerably exposed to contact with Ascaris but 
had no recollection of unpleasant effects. Three of the reactors to the skin test 
had repeatedly experienced disagreeable symptoms on exposure to Ascaris; the 
fourth was previously unaware of his sensitiveness. In one of the cases the 
symptoms were asthmatic in type. 
Different writers have reported that the characteristic odor of Ascaris may be 
detected on the breath of calves infested with Ascaris vitulorum and that the 
