322 Scientific Intelligence. 
which were found to be more efficient than white, and produced 
pupz with a color which even more resembled gold. 
(2.) Mutual Proximity.—The larve being dark, it was found 
that when many of them became pupz on a limited (white or gilt) 
area, the pupze were darker than when they had been more iso- 
lated. The colors of each were in fact affected by that part of 
the surroundings made up by the black skins of its neighbors. 
(3.) Ilumination. — Black surroundings produced rather 
stronger effects in darkness than in light, but the pupz were 
dark in both cases. 
(4.) Zime of Susceptibility—The mature larve, after ceasing 
to feed, wander (stage i) until they find a surface on which to 
pupate; they then rest upon it (stage il), and finally hang, head 
downward, suspended by their last pair of claspers (stage ill), in 
which position pupation takes place. Stage i is variable in 
length, stage ii may be estimated at 15 hours (but it is also 
variable), while stage ili is fairly constant, and lasts about 18 
hours; while the whole period is commonly about 36 hours in 
length. The larve are probably affected by surrounding colors 
for about 20 hours, before the last 12 hours of the whole period, 
and in this time the pupal colors are determined. These facts . 
were discovered by a very large number of experiments, in which 
larvee were placed in surroundings of one color, and then after a 
variable time were transferred to another color producing an 
opposite effect. It was thus found that stage ii is more sensitive 
than stage iii, although there is some susceptibility during the 
latter stage. 
(5.) The Part of the Larve which is Sensitive to Color. 
(a) Zhe Ocelli.—The most obvious suggestion was that the 
larval eyes (or ocelli, six on each side of the head) saw the col- 
ors, and being influenced, transmitted an impulse to the nervous 
centres which regulate the formation of the pupal colors. When, 
however, these organs were covered with black varnish, the pupze 
resembled surrounding surfaces to the same extent as when they 
were produced from normal larvee. 
(6) The Complex Branching Spines.—It seemed possible that 
these structures might contain some organ which was influenced 
by the color, but after cutting them off, the larvee remained nor- 
mally sensitive. 
(v) The General Surface of the Skin.—This was tested by 
conflicting color experiments. It had been previously shown 
that the larve were sensitive during stage ili, and therefore they 
were covered in this stage with compartmented tubes, so con- 
structed that the head and anterior part of the body hung in the 
lower chamber of one color, while the posterior part of the body 
was in the upper chamber in another color. In another method, 
the larve were hung upon a vertical surface, while the head and 
front part of the body passed through a hole in a shelf, the verti- 
cal surface above the shelf, and the upper side of the shelf itself 
being one color, while the vertical surface below the shelf and 
the lower side of the shelf were of the color tending to produce 
