202 



COLORATION IN LEPTINOTARSA. 



The experiments in this series were conducted in the years 1900 to 1904, 

 and were carried through ten lineal generations. The conditions of temper- 

 ature and moisture were as follows : 



Table 04. Temperature and humidity conditions. 



In this series of experiments 21 per cent died in the larval stage and 9 per 

 cent in the pupal, while 70 per cent appeared as imagines with the color mod- 

 ifications described in experiment 23. Throughout the whole series the great- 

 est care was taken to prevent the conditions of experiment from having any 

 possible influence upon the germ cells in their growth periods and during 

 maturation and fertilization. This was accomplished by removing the adults 



Parent stock, Cold. Spring liarbor. 

 Long Island. U. V. 



Exp. 27b, 

 GENERATIONS rootro1 kept in normal conditions. 



Exp. 27a, 

 subjected to conditions of experiment 



I 



II 



III 



IV 

 V 



VI 



VII 



VIII 



IX 



X 



27b 



t 

 27b 



27b 



27 b 



~27b ' 



"J", 



27b ' 



27V 



2jfa~ 



27s 



27a 



27 a 

 25a 



27b~ 



4- 

 27b 



I 

 27b 



27b 



27a ! 



2%a* 



27a ' 



4. , 



27a' 



27a 

 27a 

 2^a 

 27a 



27a 



27a' 



27a' 



I 

 27a' 



27a 

 27a 

 27a 



l?Va" 

 27a" 



Text-figure 17. The relation of the various parts of experiment 27. (The generations underscored 

 were subjected to the conditions of the experiment: those not underscored were kept in natural 

 surroundings.) 



to normal condition during the period of germ-cell growth and fertilization, 

 the fertilized eggs being returned as soon as laid to the conditions of experi- 

 ment. By this means the color changes induced by these experiments were 

 known to be purely somatic modifications. Moreover, a control series, 

 derived from the same parents, was kept under normal conditions as a check. 

 During the series also several lots were taken from the experiments and 

 placed for several generations in normal conditions, and were then returned 



