262 PROCEEDINGS OF THE AMERICAN ACADEMY 



Weismann contends that all those patterns and colors possess only 

 a biological value. The green color, which first appears, corresponds 

 to that of the leaves. But in a large caterpillar one main color 

 would be too apparent ; therefore longitudinal lines separate the main 

 color into several fields and diminish the danger, the more so when 

 the caterpillar lives among grasses. The oblique lines afford a similar 

 protection, and are even more effectual when the lines have colored 

 borders, which make them resemble the ribs of leaves. The eye- 

 spots of Chaerocampa are said to frighten enemies, and the variegated 

 colors of Deilephila to designate them as not eatable. The dark 

 color of full-grown caterpillars of Chaerocampa is said to be owing to 

 the impossibility of being protected by any color, on account of its 

 large size. These caterpillars acquire, therefore, the habit of feeding 

 at night, and hide themselves during daytime under dead leaves. 

 As, therefore, every one of the quoted characters is of biological 

 value, they can be explained by means of natural selection, and the 

 necessity to admit a phyletic, or inborn power (immediate, designing, 

 or ordaining power, Crooke) does not exist. The possibility of the 

 existence of such a power is rejected by Weismann. 



The conclusions and statements of Weismann are based upon a 

 number of European species. But it seems that the study of exotic 

 species will show that some of these conclusions cannot stand, or will 

 lose at least a large part of their value. The colorlessness of the 

 newly hatched caterpillars is perhaps not witliout exception in some 

 tropical species. The succeeding green color belongs to the hypo- 

 dermal colors, but all the longitudinal and oblique lines and the spots 

 belong to the dermal colors. The dorsal line is the consequence of 

 the situation of the dorsal vessel ; j^robably the subdorsal line and the 

 oblique lines are muscular lines, and the stigma line a consequence of 

 the large longitudinal tracheas. 



The large eye-spots on the thoracical segments indicate the place 

 under which the wings are beginning to be formed. Similar spots, 

 but less strongly developed, are to be found in a number of larvae 

 of Myrmelionidae. The formation of the wings necessitates a largely 

 accelerated circulation in those places, and therefore an oxidation of 

 the cuticula. These eye-spots belong to the dermal colors. The 

 very remarkable eye-spot in Pteror/on (^Thyreus) Ahbottii appears in 

 the third stage exactly on the same place where before the tailed 

 appendage existed. The change in this species is very interesting. 

 The second stage has as main color a very light grayish pink, and 



