REPORT OF THE SOCIETY 35 



but to bots and parasitic worms. As regards the practical significance of the 

 reaction, it may be found to furnish a useful index of the presence or absence of 

 parasites in a mammalion host. For instance, the instilling of a tiny drop of 

 warble extract diluted in water will cause a copious flow of tears and conjuncti- 

 vitis, if the animal is or has been affected by warbles. The injection of bot 

 extract in a cow will not produce any effect, since cows are not parasited by bots 

 and therefore have not been rendered sensitive to the particular proteins of bots. 

 Extracts of adult warbles and bots will produce the same reactions as the larvae. 



In conclusion, it should be remarked, as the experiments of Hadwen and 

 Bruce (Joe. cit) show, that the test is not always infallible, and some animals may 

 develop a condition of immunity which will produce negative results even on 

 repeated injection of the specific protein. This immunity is not very well 

 understood. 



From a practical point of view the enlargement of our knowledge on this 

 particular set of reactions has been the means of offering a satisfactory explanation 

 of the serious effects which often follow the abrading and bursting of the warbles 

 on the backs of cattle, whether this arises from rough handling of animals or 

 accidental circumstances. The animals may die of anaphylactic shock. Similarly, 

 the small oedematous swellings — called by Hadwen^ (p. 7) "hypodermal rash" — 

 produced at the point of entrance of warble larvae into their hosts, are an indica- 

 tion of the animals' response to the reaction. 



BOTS. 



Introduction. 



Three species of bots are known in America; but whereas Gastrophilns in- 

 testinalis DeG., the common horse-fly, is widely distributed throughout the coun- 

 try and is best known because of its abundance and comparatively slow flight, 

 the chin fly, G. nasalish., and the nose fly, G., Imemorrhoidalis L., do not 

 seem to enjoy the same wide distribution. It is just possible, however, that 

 nasalis will be found throughout Canada, both east and west. Bishopp^^ (p. 183) 

 has traced its presence in most of the states of the union. G. haemorrhoidalis, 

 which is perhaps the most annoying of the three species in its habits of ovipositing, 

 is less known than the other two species and has often been confused by the lay- 

 man with nasalis. Bishopp iloc. cit.) has established its presence in eight states of 

 the west and middle west, its eastern distribution extending to the state of Wis- 

 consin. In Canada, the author and Hadwen have records of its presence in Al- 

 berta, Saskatchewan and Manitoba. 



