26 Gil ruth anfl Stueet : 



We have previously noted the fact that amonf);st the large number 

 of nodules which we have examined, the female parasite was either in 

 a stage of complete development lil)erating living larvae, or the nodules 

 contained degenerated parasites ; in other words, no immature parasite 

 has ever been found in a nodule. With these two cows for a period of 

 6 and S months there was absolutely no possibility of reinfection. 

 Many of the nodules could be felt under the skin, and as a number of 

 these subcutaneous nodules were found />o'<t mortem to contain living 

 Onchocerca liberating living larvae, it must be assumed that they had 

 been continuously liberating such larvae during the whole period, for 

 as the male lies continuously alongside the female, there is probably 

 continuous fertilisation of the latter. 



We have in the previous paper indicated the probability that infec- 

 tion of the bovine takes place during its early years (1st and 2nd) 

 alone. Corroboration of this was obtained by J.A.G. and Dr. Breinl 

 when in the Northern Territory ; on one station, the station on which 

 the steer with a hundred nodules had been bred and fattened, an oppor- 

 tunity was obtained of carefully examining two verj' old bullocks. 

 In one, only one small nodule, and that containing a living parasite, 

 could be discovered; in the otlier, a few small, circumscribed, thin, 

 circular or oval dense fibrous masses about ^ to f inch were found 

 adhering firmly to the muscular fascia. Section showed a calcareous 

 centre. Judging from the invariable infection with living Onchocerca 

 of younger cattle on this station, two conclusions seem fairly obvious— 

 1st, there is little, if any, reinfection after a certain age; and '2nd, 

 the tendency is for the nodules to becoiue greatly diminished and 

 ultimately disappear. 



Intepmediary Host. 



As indicated in our previous con)munication there are several possi- 

 bilities with regard to the int<'iiuediale hcjst, whicii we h.ivt- aliciidy 

 shown must be present, though, as there stated, the evidence then avail- 

 able appeared to point to a biting insect, and especially the louse, as 

 being the responsible agent. 



Since then, experiments at that time in progress have been com- 

 pleted, the investigations in the Nortlicrn Territory above referred to 

 hiive been made, and several other series of experiments have been 

 carried out with the object of testing conclusively whether the infection 

 may be brought about by direct contact, by intermediation of the soil, 

 or by either of the lice normal to the cow, and as to whether perchance 

 an adult w^orm or the larvae may leave a nodule and infect tlie same or 

 other animal, thus rendering an intermediary host unnecessary. 



