63 
Such facts as these show that the various color t3^pes may develop 
among- bollworms grown as nearly as possible under similar conditions, 
and sugg-est that the matter is entirely an hereditar}^ one. Neverthe- 
less the apparent predominance of certain types on various plants and 
under different conditions led us to undertake some experiments along 
this line. Six lots of ten larvae and one of three were fed on cotton, 
tobacco buds, tomato buds, Irish potatoes, flowers and buds of cow- 
peas, corn silk, and the leaves and spikes of Amarantiis spinosits^ 
respectively, but variations peculiar to each lot did not appear. The 
experiment was later repeated with twent}^ larvae from eggs of a single 
moth, fed on cotton, tomato, potato, and tobacco, but afforded no fur- 
ther results. Other experiments were tried b}^ rearing larv^ in moist 
and dry atmosphere, and in light or dark situations, but no evidence 
was secured. Cold weather influences to some extent the color of the 
head. Normally this is black in the first stage and pale in the others, 
but in the spring and fall and in the ice box, the black color persisted 
through the second stage. 
In the field numerous variations, presumably due to environment 
were noted. Among larvae feeding on cotton, the pale pink or green 
tj\)Q is apt to predominate, except when feeding on the foliage, when 
bright greens and yellow make their appearance. On corn all three 
types occur at nearly all times, although green individuals with crim- 
son spots are rather scarce in midsummer. On alfalfa a uniform green 
type is most common. These dark greens, noticed in specimens feed- 
ing on foliage, may be due in great part to the bright-green color of 
the blood under such conditions. 
DURATION OF LARVAL IN STARS. 
This question was worked out very thoroughl}^ by Mr. Girault in 
the laboratory at Paris during the season of 1904. Some thirt}^ lots 
were reared with this object in view and the molts recorded as accu- 
rately as possible down to hours. The number is too large to represent 
consecutive generations, and the life cycles of the different lots overlap 
one another more or less. The following table summarizes the entire 
number: 
22051— No. 50—05 5 
