298 Mr. ^onlton's further experiments vpnn 



I. Dark Scrrodndings. 



Dead leaves, &c., intermixed 



with food-plant. 



II. Green 



Surroundings. 

 Food-plant alone. 



I III. Green 



Surroundings. 

 Food-plant alone. 



Sept. 19. — 1 H. oleracea, dead, 

 was brown ; 1 ditto, pupating, 

 was brown ; 1 ditto, changing 

 skin, was brown ; 2 ditto, feed- 

 ing, were perhaps darkening. 



1 M. hrassicce, dead, was brown ; 



2 ditto, feeding, were brown. 

 There was also 1 pupa of hras- 

 sicce. 



Sept. 19. — Only 2 brown larvae, 1 hras- 

 sicce and one oleracea ; the others remained 

 1,'reen. All were dead except 3, but their 

 colours could be made out. 



The results are not at all satisfactory or convincing, 

 because the larpje proportion of deaths shows that the 

 larvae were not kept in a normal and healthy condition, 

 and especially because of Miss Gould's negative results 

 with more successfully conducted experiments upon 

 Mamestra hrassicce (Trans. Ent. Soc. Lond., 1892, p. 215). 

 At the same time, I should be glad for further experi- 

 ments to be made, especially with //, oleracea and E. 

 lucipara. The investigation is far more difficult with 

 such Noctiue as these than with the genus Catocala or 

 with Geometrce. The larvse tend to bury or conceal 

 themselves low down on the plant. The abundant 

 faeces very quickly produce the effect of dark surroundings, 

 and, being moist, promote decay in the food-plant. Hence 

 it is very difficult to keep the conditions uniform, and in 

 addition to this, the larvae are apt to become stained by 

 the semi-liquid material on the floor of the case. Ail 

 these difficulties could, of course, be obviated, but this 

 would require much time and constant attention. These 

 experiments were conducted at the same time with many 

 other lines of work, and did not receive sufficient care. 



I may, however, claim that the results point to the 

 desirability of further investigation upon these or similar 

 dimorphic species. 



2. Experiments in 1886 upon Mamestra persicari^. 



These experiments were also conducted upon captured 

 larviB, and are open to the same objections as those just 

 described. They are given in a tabular form below : — 



