GASTROPHILUS HAEMORRHOIDALIS AND OTHER BOTS. 33 



observed feeding upon flowers, but green twigs were favorable resting- 

 places in rearing cages. 



A female taken while ovipositing was placed within a tube contain- 

 ing a male, and they were observed to copulate for 5 minutes. 



Dissections of 5 females showed the following; egg capacity : Maxi- 

 mum, 770; minimum, 397; average, 541. 



INCUBATION AND INGRESS OF LARV^. 



While making observations in pastures, on four occasions large 

 numbers of eggs were collected which had been deposited upon the 

 author's horse, The eggs were kept in tubes at air temperatures of a 

 living room and none hatched without friction and moisture. By 

 placing the infested hair upon a microscope slide and moistening it 

 the larvae were most easily removed by rubbing; the lot with a dis- 

 secting needle. In such tests the eggs remained attached to the hair, 

 while the operculum was removed, allowing the larva to emerge. 

 Very good results were also obtained by rubbing a moistened finger 

 over the lot. When eggs were less than 7 days old it was found diffi- 

 cult to obtain living larvae, though at 9 and 11 days active larvae were 

 removed. When they were slightly older than 11 days they emerged 

 without difficulty when attended by moisture and friction, and one 

 living larva was found as late as the forty-eighth day. This seemed 

 to be an exception, as in the other lots all were dead after 40 days. 

 In general, all experiments tended to confirm those of Osborn. Ac- 

 cording to Guyot, with various lots placed in paper bags and kept 

 in a pasteboard box at room temperatures, some emerged without 

 moisture and friction. On December 28, 1900, Guyot obtained 

 quite agile larvae as late as 96 days after collection of the eggs. 

 In another case, with eggs collected on October 6, he succeeded 

 in obtaining larvae from January 7 to 13 following, a period of 92 

 to 98 days. Due to this fact, Guyot concludes that the larvae are 

 capable of withstanding comparatively low temperatures after the 

 eggs have been removed from the host. From eggs collected on 

 horses in the open, active larvae were removed as late as December 1. 



LARVA STAGES. 



The attachment of young larvae frequently occurs in almost any 

 part of the stomach, but. as has been previously stated, they are 

 found as fourth-stage larvae upon the mucosa of the stomach, more 

 especially on the left sac. If living larvae are removed from an 

 animal during a post-mortem examination a great tendency for re- 

 attachment will be observed. During such examinations they have 

 been frequently separated into lots according to species, and in a short 



