100 S. HADWEN AND A. E. CAMERON. 



so, indeed, that quite a little force had to be exerted in detaching them. When 

 examined the following morning (19th Sept.) all were found to be dead, probably 

 from the effects of the salt solution. None had made any further progress in their 

 efforts at entrance than was observed the previous night. The experiment was again 

 repeated on 21st September, but on this occasion two pieces of mucosa with the 

 attached muscles, taken from a horse's tongue were used. One of the pieces was 

 papillated, the other unpapillated. In the case of the first, 12 newly-hatched larvae 

 •of G. intestinalis failed to effect an entrance, but out of 4 larvae on the unpapillated 

 portion, one succeeded in becoming completely buried in 8 hours after the experiment 

 was commenced. After 6 hours, only the terminal spiracle-bearing processes were 

 showing, and these were finally lost to sight. 



The success of this last experiment stimulated the authors to make a further 

 attempt, which was done in the laboratories at Agassiz, B.C., later in the season. In 

 all, four experiments were made on 22nd October, with larvae hatched from eggs 

 collected at Duncan, Vancouver Island, on 15th October. The larvae readily emerged 

 when the opercula of the eggs were detached with needles. In each case the mucosa 

 of the tongue of a calf just killed was used. For the first, the portion selected was 

 unpapillated, taken near the tip of the tongue ; for the others, papillated. 



Briefly stated, the results were as follows. In experiment No. 1, of 10 larvae 

 placed on the skin at 12.45 p.m., 6 began burrowing and effected an entrance. In 

 •only one case did the larva succeed in completely burying itself, and this occurred 

 7 hours after the experiment commenced. In the other cases, only partial success 

 attended their efforts, and the progress made varied considerably. For instance, 

 after 6 hours, 3 larvae had 3, 5 and 7 segments respectively still revealed, and another 

 after 7 hours, had still 4 segments visible. 



In experiment No. 2, of 6 larvae, one burrowed completely beneath the surface 

 in 2| hours, in close proximity to a papilla. In experiment No. 3, of 5 larvae, 2 

 effected an entrance and, in each case, became completely buried in about 4 hours. 

 A third was only partly successful, all the segments being hidden except the last 

 three, in 1 hour and 40 minutes. No further progress was, however, achieved. 



In experiment No. 4, of 6 larvae, 2 burrowed beneath the surface and disappeared 

 in 2i- hours. In both cases they effected their entrance by means of the circumvallate 

 fossa of a fungiform papilla. In this particular experiment, the larvae proved very 

 restless, at times travelling aimlessly around, and at others, settling down and making 

 an attempt to enter. Some appeared to be partly successful in their efforts, but 

 ■after a while they would withdraw their mouth-hooks and wander around restlessly 

 again. In the third case, in which entrance was successfully effected, 8 hours were 

 occupied in the process, the larvae being finally oriented at a sharply oblique angle 

 with the surface. 



In summing up the results of these experiments, we do not wish to attach too 

 much importance to their significance, although they are certainly suggestive. 

 Granted the larva finds its way to the mouth of the host, there is apparently no 

 reason why it should not penetrate the mucous tissues therein. Indeed, its structure 

 is admirably adapted for this purpose, as is readily seen when one considers the 

 piercing function of the mouth-hooks and the backwardly-directed segmental 



