Color Variation in Sea Hare — Winkler 
in extracts of Plocamium pacificum nor did they 
show a relationship with Aplysia purple. 
It was also noted that several hours after 
removing a dead A, calif ornka from sea water, 
the brown epidermal layer of the skin can be 
rubbed off. In the red-streaked, Plocamium- 
feeding animals it was found that beneath 
this layer, on the surface of the unpigmented 
dermal layer, were broad, purplish red streaks 
of deposited material. In life these streak 
marks appear red, as the result of the filtering 
action of the thin epidermal layer. These 
streaks interconnect to form a reticulum 
which is most pronounced on the sides, 
especially near the margin of the foot. 
The streaks were rapidly dissolved in dilute 
hydrochloric acid, dilute acetic acid, and 70 
per cent alcohol, the latter changing the gross 
color to yellow. The acid extract consistently 
gave a strong absorption peak at 548 m^ 
(Fig. IC) with an irregularity in the curve at 
490 m/jL. The nature of this irregularity sug- 
gested to the writer that the curve might be a 
composite. The streaks were differentially ex- 
Fig. 1, The curve shown in A is produced by the 
water soluble fraction of the subcutaneous purple 
streaks, while that in B is produced by a subsequent 
acid extraction. The total spectrum of the two com- 
ponents is shown in C. No attempt was made to make 
the several extracts quantitative. 
65 
tracted with distilled water and dilute hydro- 
chloric acid. In the former the streak-coated 
tissue was soaked overnight. The resultant 
extract was a light yellow and the gross color 
of the streaks had changed somewhat. The 
streaks were then completely dissolved in 
dilute hydrochloric acid in a few minutes. 
The water extract showed peaks at 548 and 
490 mjjL (Fig. IB). The acid solvent contained 
a component with absorption maxima at 503, 
520, and 548 m/x, the one at 548 being broad, 
the other sharp (Fig, lA). No attempt was 
made to employ quantitative techniques so 
the relative height of curves A and B are 
probably not correctly portrayed. When the 
two are dissolved together the additive effect 
produced the curve in Figure IC. 
Upon neutralizing the composite extract of 
the streaks, the color completely disappeared. 
Upon reacidification the color was reconsti- 
tuted without significant spectral change, but 
if made strongly alkaline, a jell-like precipitate 
formed. 
DISCUSSION AND CONCLUSIONS 
The reversion of specimens of all available 
color patterns to a common pigmentation 
when fed a common diet demonstrated the 
dependence of these animals on food pig- 
ments for their coloration. The land plants 
which supplied principally chlorophyll as a 
pigment lacked the special pigments which 
are normally obtained by these animals from 
their algal diet. It seemed logical to search for 
the cause of the red streaks from among these 
special algal pigments. 
The consistence with which Plocamium 
pacificum was found in the fecal pellets of the 
red-streaked animals led to experiments with 
that algal form. Feeding experiments involv- 
ing Plocamium over the extended period 
necessary to produce red streaks were imprac- 
tical because of the perishable nature of the 
sea weed. However, single large feedings pro- 
duced a pinkish cast on the bodies of parsley- 
fed experimental animals, caused by the 
blood’s becoming temporarily purple. 
