^227 Indian Museum Notes. [Vol. IV. 



On the twenty- seventh day out of forty-three eggs opened only 

 one larva was alive, and on the twenty-eighth day only one out of 

 sixty-five, and on the twenty-ninth day all the remaining eggs, one 

 hundred and three, showed only dead larvae. 



The results of this study, it will be seen, confirm in the main the 

 conclusion of the former observations, the principal ilifference lying 

 in the fact that all the larvae were dead at a somewhat earlier period. 

 Of course it could not be said that of the eggs opened in the earlier 

 days none would have survived longer than four weeks, but consider- 

 ing the number used and that one-third of them were kept the full 

 four weeks, and two-thirds nearly that long before being opened, the 

 presumption is strong that that is the full normal period of survival. 



It is safe, I think, to sum up the matter by saying that the eggs 

 normally require friction and moisture to permit of their hatching and 

 transfer to the horse's mouth, that hatching occurs with difficulty 

 before the tenth day, and most readily after the fourteenth day, and 

 that they lose vitality at a period varying between the twenty-eighth 

 and fortieth days, the bulk not surviving more than four weeks. 

 This gives a solid foundation upon which to base recommendations 

 as to the time when eggs must be destroyed. 



The newly hatched larva is a slender, worm-like creature, so 

 transparent that the internal organs are plainly visible. It grows 

 rapidly at first, its food consisting probably of the mucous secretions 

 of the mouth and oesophagus. ...... As soon as it 



reaches the stomach it fixes itself to the walls by the hooks next 

 the mouth and soon undergoes considerable change in its form and 

 appearance. The body becomes more conical, but instead of the head 

 end being widest this becomes more slender, while the tail end 

 broadens. The spiracles at first exposed in two flap-like projections 

 from the last segment are drawn more within the body and are pro- 

 tected by the development of a horny plate. The spines on the 

 segments following the head become more pronounced. When full 

 grown the larva is three-fourths of an inch to one inch in length 



At this time they occur in large clusters upon 



the walls of the stomach, generally more especially numerous at 

 the pyloric portion, where they serve to retain the contents of the 

 stomach. From the fact that the food of the horse does not become 

 •completely reduced to fluid, this obstruction may be considerably 

 greater than if only fluid matter had to pass the pylorus. This 

 growth has occupied from late in the fall, through the winter, till 

 late in the spring, and when fully developed the bots loosen their 



