the Growth and Habits of Carausius morosus. 363 



I think the normal emergence is by the pronotum 

 coming out first, followed more or less simultaneously by 

 the head and mesonotum, etc. That would correspond to 

 the position of the nymph when about to slip out of its 

 old skin at every ecdysis. 



Increase in Length during the First Twenty-four 

 Hours after Emerging from the Egg. 



The growth of the nymphs from hatching out to the 

 first ecdysis is perhaps not the least interesting part of a 

 stick insect's life. As a preliminary to the investigation 

 of this growth it was necessary to obtain accurate measure- 

 ments of the size of the young immediately after emergence. 

 To overcome the difficulties of accurately measuring living 

 specimens the newly hatched young were, for several weeks, 

 immediately killed and then immediately measured. 

 The results of the measurements of 932 newly hatched 

 young are shown graphically in Diagram II. The measure- 

 ments were made to the nearest half-millimetre. The 

 upper curve gives the details of the actual measurements, 

 and the lower curve expresses these results in the form of 

 percentages of the total number measured. The range in 

 size of the newly hatched young is from 7'5 mm. to 12"5 mm., 

 and the curve representing this range shows a more or less 

 gradual rise with certain irregularities to 10"5 mm., a sharp 

 maximum at 11 mm., and a less gradual fall to 12 - 5 mm. 

 The average size of these 932 specimens is 10'5 mm., which 

 is very close to the maximum of the graph. The results 

 appear to indicate that a certain proportion of the nymphs 

 are hatched out before the normal size is attained. Hence 

 25*5% of the hatchings, i. e. those under 10 mm. in length, 

 might be expected to undergo one ecdysis more than those 

 hatched out above that length ; but this does not occur 

 in so far as my experience goes, for such undersized nymphs 

 as I have kept under observation went through the same 

 number of ecdyses, i. e. six, before arriving at the same 

 perfect state as those hatched 10 mm. long or over. 



When newly hatched nymphs are placed on the upper 

 side of a leaf they behave in various ways, viz. they rarely 

 feign death, they remain stationary, or they walk to the 

 edge of the leaf and attach themselves to the underside, 

 or in their struggle to get away they run off in an excited 

 manner with the abdomen curled over backwards (very 



