REPORTS OF ORSERVATIONS AND EXPERIMENTS 1< 



fact that two or three flies were at the time depositing egga on the 

 animal, it seemed probable that a good share, at any rate, of those 



obtained had been recently deposited. It occurred to me to make some 

 observations on the time and conditions when the would batch, 



and the following record is the result: On September 23, four days 



after collection, the eggs, when moistened, showed distinct dark bands 

 with rows of black spines upon the segments, indicating a well devel- 

 oped condition of the embryo, but there was no tendency to hatch and 

 the egg when opened showed the embryo to be only slightly active, its 

 movements being slow, and it would appear that it was not really 

 ready for hatching at that time. An effort to hatch them by rubbing 

 was not made at this time but the eggs opened by picking off the cap. 

 On the following day, September 24, the eggs previously moistened did 

 not hatch, but one egg, upon being moistened and rubbed for some time 

 with the end of the finger in a manner to simulate the action of the ho 

 tongue, was hatched, and adhered to the finger. This specimen was 

 fairly active, especially the hinder portion of the body. This must ha ve 

 been at least five days after deposition and, of course, may have been 

 longer than this, as some of the eggs may have been deposited some 

 days previous to the time of collecting. On September 25 the two i 

 which were first moistened but not rubbed were still unhatched. and it 

 would appear from this that moisture alone is insufficient to produce 

 the hatching, at least during the earlier time following deposition. On 

 the next day another egg was hatched by moistening and rubbing and 

 by also picking the cap of the egg with a pin. The rubbing alone did not 

 succeed in hatching it, although continued for a long time, but when 

 the lid was picked with a pin the larva appeared active and it would 

 seem perfectly capable of all movement necessary for migration to the 

 stomach. On September 27 another specimen was hatched, but this was 

 also hatched with difficulty, the cap being removed finally by slight 

 pressure with a needle point, the larvae, as in previous cases, appearing 

 active. On September 28 another egg was hatched in the same man- 

 ner as the preceding one, the cap being removed with difficulty but the 

 larva active. It would seem from this that for at least ten days the 

 hatching occurs with difficulty and if these were average specimens it 

 would hardly be possible with the ordinary movement of the tongue to 

 secure the release of the larva'. Some days elapsed before another 

 effort was made, but on October 21 another egg was tried and this one 

 hatched almost immediately upon being touched with the moist linger. 

 the larva adhering to the linger and wriggling about with great activity, 

 so that it would certainly have had every opportunity to find the con- 

 ditions for its survival, On the same day two other eggs were opened, 

 the lid* being removed very quickly by being moistened with the finger, 

 but the lar\;e from these two eggs were inactive, apparently dead, 

 and this would seem to confirm the view that the larva- die without 

 issuing or breaking the cap from the egg unless moisture or rubbing is 



