132 
Loa papionis n, sp. 
skin of the anterior abdominal wall, while the third was lying dead in the 
region of the wound; of the two males, only one was found and this with some 
difficulty—it had hidden itself in the connective tissue between the right 
hamstring muscles. All fat had disappeared from the body, otherwise the 
organs seemed healthy. No larvae were noticed either in the peripheral blood, 
the heart’s blood, or in smears from the various organs, but two were seen in 
a smear made from the connective tissue in which a female had been found; 
eosinophiles were not a marked feature of the preparation. The three living 
Loas removed at the autopsy of guineapig no. II were left for two hours in 
normal saline and then introduced into another guineapig. 
I was unable to continue these experiments owing to the war and killed 
the animal the day after. All three worms were found in situ and their move¬ 
ments were as vigorous as when taken from the baboon ten days earlier. 
Guineapigs nos. I and III were killed at the same time. No Loas were found 
in no. I in spite of a careful search; they had almost certainly escaped from 
the wound shortly after the operation. Both animals were healthy. 
Conclusions. Although the possibility of guineapig no. II having died of 
some undiagnosed infection was not absolutely excluded, it seems more 
reasonable to suppose its death to have been occasioned by the presence of 
the Loas. 
The reaction of the host. The following facts point to the possession of a 
considerable, though variable, degree of immunity against Loa infection by 
the adult baboon. 
(a) Out of the fifty-five baboons examined only thirteen (23*6 per cent.) 
were found to be infected. 
(b) The degree of infection was very variable in the parasitised animals. 
Neither males nor larvae were present in one case; in another, forty-three Loas 
were found, while the blood was swarming with larvae. 
( c ) The apparent absence of immature Loas in the tissues of infected 
animals points to the existence of a high degree of immunity against reinfec¬ 
tion in the adults. 
E. The Treatment of Filarial Disease. 
The mechanism of immunity in filariasis and the possibility of manufac¬ 
turing prophylactic and curative antisera against these infections are subjects 
which have as yet been very imperfectly investigated in man. Yet the ap¬ 
parent toxicity of Loas for guineapigs, together with the undoubted immunity 
possessed by adult baboons against Loa infection, point to the production of 
toxin by the Loas and antibody by the host. Moreover it is possible that such 
antibody exists in sufficient quantity to effect a cure of Loa infection when 
baboon serum is introduced into human beings; for Query (1918) has recently 
reported the case of a patient who, after receiving a course of antisyphilitic 
serum, wrote to the effect that the Loa infection from which he had suffered 
up to the time of the injections, had been apparently cured by them. 
