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Prof. E. W. MacBride and Miss A. Jackson. 



An apparently pure green may become olive-green in the fourth instar, 

 and may remain so, or- it may become light brown and, finally, dark brown, 

 or from olive-green it may become reddish-brown. 



Yellowish-browns appear in the fourth instar, and the colour may deepen 

 into hazel. A very curious and exceptional change is that a red-brown 

 appearing in the second instar may develop into green suffused with brown. 



Proportions of Colours — Varieties in the Offspring. 



In October, 1912, 30 adult females were isolated in glass jars, and allowed 

 to lay eggs. The eggs hatched in April, 1913, and the emerging insects 

 were reared to maturity, and the proportion of colour varieties produced was 

 ascertained. 



The mortality amongst these insects was very high. Out of a total of 

 174 insects reared 147 were green and 27 brown, giving a ratio of between 

 5 and 6 green to 1 brown. The most interesting result was that the 

 colour of the parent made no difference in the proportions of colour 

 variations found in the offspring. To give instances : Out of 10 insects, the 

 offspring of a brown female whose mother was also brown, 8 were green 

 and 2 brown. Again, out of 14 insects, the offspring of a green female 

 whose mother was green, 11 were green and 3 brown. From a green 

 parent whose mother was brown, 13 insects were reared, and of these 11 

 were green and 2 brown. 



This result was sufficiently unexpected to whet the desire for more 

 detailed knowledge. It is open to two objections. First, the proportion of 

 larvas which survived is small, and, secondly, from some of the original 

 batch of eggs from which the material was derived one male was reared. It 

 was, therefore, determined to repeat the experiments, taking precautions to 

 keep the atmosphere warm and moist during hatching. 



In August, 1913, 40 females 1 in the fourth and fifth instar were isolated, 

 and placed each one in a separate jar on a food plant. These females became 

 adult in September, and laid eggs in October and November, and throughout 

 the winter. One insect continued to lay till September, 1914, and laid in all 

 500 eggs. 



The eggs produced by each specimen were counted and placed in a pill 

 box. They were sprayed once or twice a week in order to prevent them 

 becoming too dry. The eggs began to hatch in April 1914. As hatching 

 was spread over a considerable time, maturity was reached at very different 

 times by the different families, and so from time to time counts were made 

 and the adults removed. The first of these counts was in September, 1914, the 



