The Inheritance of Colour in Carausius morosus. 117 



concluded that green insects can be produced in perfect darkness and in the 

 entire absence of chlorophyll. 



The experiment was also tried of keeping the insects in continuous light 

 day and night. The light was supplied by a 16-candle-power electric bulb. 

 Twelve just-hatched insects were selected for this experiment. Instead of 

 resting by day and feeding by night they fed by night as well as by day, and 

 when resting did not assume the protective position. The insects were kept 

 under perpetual light conditions from May 20 till February, with the 

 exception of a fortnight in August. They became adult in September, and 

 "were fully six weeks in advance in development of other insects brought up 

 under normal conditions. All were green. 



General Conclusions. 



The series of unexpected facts brought to light by this investigation do 

 not fit in easily with any current theories. They lead to the following 

 conclusions : — 



(1) All stick-insects of the species Carausms morosus are born alike. All 

 have a definite colour pattern of green and brown pigments. 



(2) As growth proceeds, in the vast majority of the cases the green 

 pigment overpowers the brown so that the pattern disappears, and the 

 insect appears to the unaided eye a pure green. According to Schleip some 

 traces of brown pigment can always be detected in the cells of the ectoderm 

 of the greenest insects. 



(3) In about 3 per cent, of the cases the brown pigment increases during 

 growth and prevents any trace of green being seen, and in these cases, 

 according to Schleip, no green pigment is visible in the ectodermal cells even 

 on microscopic examination. 



(4) In a few cases where the green pigment becomes predominant the 

 brown pigment remains in sufficient quantity so as to affect the colour and 

 to give rise to the varieties known as green suffused with brown, green with 

 brown spots, etc. 



(5) In a still smaller number of cases the yellowish red pigment, which 

 appears always to be present to some extent, increases so as to give the 

 adult insect a yellowish or reddish brown colour. 



(6) The proportion of insects which acquire a predominantly green or 

 a predominantly brown colour amongst. the offspring is not influenced by the 

 colour of the mother. 



(7) Pure green insects can be raised from larvae exposed to complete 

 darkness from hatching. 



(8) Bearing insects in reduced light does not increase the proportion of 



