116 THE EEPOET OF THE No. 36 



Dr. Toeeance: Mr. President, ladies and gentlemen, it affords me very 

 great pleasure to be with you to-day, especially as one of our men has contributed 

 something towards the programme. The work which Dr. Hadwen has done is very 

 much appreciated by his chief, and I think, will be appreciated by all when it 

 is better known. He has proved a very diligent and careful investigator, and 

 I think the facts which he has hrought out will bear the closest scrutiny. He 

 has succeeded in throwing light upon a very difficult problem, the problem of 

 the migration of newly hatched warble larvae to their final resting place beneath 

 the skin of the back. The importance of this work will be realized when I tell 

 you that in Canada the leather produced is damaged to the extent of perhaps 

 7'0 per cent, by the presence of this larva. After the larva has escaped from 

 the back the scar tissue which repairs the damage causes that portion of the 

 leather to be unsuitable for the manufacture of the better grades of harness. 

 You are, perhaps, aware that in making harness, especially traces, it is necessary 

 to take long strips of the tbickest leather from along the back. This is the part 

 that is chiefly damaged by the warble flies, so that the best portion of these hides 

 is unsuitable for the manufacture of harness. In correspondence with practically 

 all the tanners of Canada referring to the damage done by this parasite, the 

 opinion was expressed that it was the greatest source of injury to the leather 

 that they knew of. There were not many other things that caused the same 

 amount of damage. The injury caused by barbed wire fences, warts, etc., was 

 trivial when compared with the damage caused by this warble fly. It is only 

 by the close study of the life-habits of a parasite that we can arrive at the best 

 possible means of combating it and we hope that the result of this work of Dr. 

 Hadwen's will be some practical method whereby the damage caused by this 

 insect can be avoided. I was greatly interested, too, in the paper read by Pro- 

 fessor Lochhead, in the damage he describes in horses, as we have had practical 

 experience with the effects of these parasites on horses. The more common is 

 the one to which he did not refer, the Gastropliilus equi, an extremely common 

 parasite of horses. In my experience covering thirty years of active practice I 

 may say that I have seldom found a horse not infested. Every horse that passes 

 a portion of its life in the open is sure . to contain these parasites. In cities 

 horses may possibly avoid them but it is very common to find them in a horse's 

 stomach. Among farmers the presence of bot larvae in a horse's stomach is looked 

 upon as the cause of the horse's death in very many cases, but when we find 

 them in horses that have died from any cause we may realize that the presence 

 of a moderate number of these parasites may be tolerated without injury to the 

 animal's health. On the other hand, we know that where they are present in 

 very large numbers they affect the function of the stomach to such an extent that 

 many derangements may take place, such as ulceration of the walls of the organ. 

 These larvae are harmless when in small numbers but in large numbers cause much 

 trouble and sometimes death. The Nose Bot Fly, which give so much trouble 

 to the farmer in the N"orth-west when he is hitching up his horses, does not 

 cause so much trouble ; it is not nearly so harmful to the horses and we have verv 

 few examples of its doing much injury, the annoyance it gives is about all the 

 harm it does. "Why the ovipositing of these two flies, the Bot Fly of the horse 

 and the Bot Fly of the cow, should occasion such intense fear in the victim 

 I do not know. We are assured by scientists that neither of these flies have 

 any stinging apparatus and yet the animal affected shows every evidence that 

 the fly must inflict much pain. I cannot imagine that the depositing of the 

 -^"•gs upon a liair would give so much discomfort to the animal. T think we will 



