Onchocerciasis in Guttle and Associated An limits. 21 



»nimal, and such variations as do occur, are independent of the 

 size of the worm. All measurements given in the paper on Oncho- 

 cerca gib&dni previously quoted (Gilruth and Sweet, 1911), and 

 those given here for Onchocerca indica, have been made under 

 identical conditions — the specimens being cleared in carbolised 

 absolute alcohol, just before measurements were made with a stan- 

 dardized screw micrometer eyepiece — so that in comparison of thesi 

 two sets of figures all extraneous influences are eliminated, except 

 any differences which might be due to a different preserving fluid. 

 Since, however, the action of the above clearing fluid freshly 

 applied in the way indicated is to " plim " the body of the worm 

 into its apparently normal condition as when living, I think this 

 may be ignored, and we may regard the figures given as strictly 

 comparable. Reference is made to figures given by other workers 

 as- indicated, since although perhaps not strictly comparable with 

 the two sets given by myself (on account of the slightly varying 

 amount of swelling or contraction caused in certain parts by dif- 

 ferent clearing reagents), they may at least be taken to indicate 

 that variations in excess of those present in the worms examined by 

 me, were encountered by these workers, so must be taken into 

 account in separating two species so closely allied as the two under 

 consideration. 



Reference to Tables -i and 5 included herein will facilitate such 

 comparison. As will be seen (Table 4), the range in length of 

 mature nude worms is considerably greater than in 0. gibsoni, O. 

 gutturosa, or 0. f>oi>is, the other forms of this genus occurring in 

 the connective tissues of cattle, the average length also being greater 

 ■than in those species. Further, the worm is markedly stouter than 

 any others, the specimens of 0. indica exceeding in average diameter 

 the stoutest of 0. gibsoni, both anteriorly and in the middle part of 

 the body. The stoutness, however, bears no relation to the length of 

 the worm, as will be seen on glancing at Bii, and Dii, and R in Tabic 

 1. In spite of this, the variation in position of the nerve ring from 

 the anterior extremity is exactly the same as found by ourselves and 

 Cleland and Johnston in 0. gibsoni, though greater than that re- 

 corded by Breinl, and less than by Leiper. Rather unexpectedly, 

 moreover, in the two longest specimens of 0. indica, I find that it 

 is slightly further forward than in the others, though one would 

 naturally have thought to find the reverse. The oesophagus of the 

 male again always exceeds in length the highest range given for 

 0. gibsoni by all workers, except Breinl, and, as a rule, that found 

 in 0. gutturosa or 0. bovis, while in diameter it greatly exceeds 



