272 EXPERIMENTS AND OBSERVATIONS 
the lower side is pigmented, it is also provided with scales or 
tubercles like the upper, thus proving that the lower side has in 
the abnormal specimen formed itself after the pattern of the upper 
side, and not after the pattern of a remote ancestor. It has never 
been maintained, as Mr. Holt suggests, that this unusual develop- 
ment of dermal armature on pigmented lower sides has anything to 
do with the action of light; on the contrary, I have always main- 
tained that abnormalities of coloration occurring in nature are 
independent of the action of light on the individual. 
The subject is too complicated to be discussed at any length here, 
belonging as it does to the intricate problems of ontogeny. But 
one interesting consideration may be mentioned. In a piebald plaice, 
such as the specimen here recorded, the unpigmented areais exposed 
to light as much as the rest of the upper side, and yet it remains 
unpigmented. How then, it may be asked, can it be maintained that 
pigment is developed on the lower side of a normal specimen by 
exposing that side to the light? Some may be inclined to believe 
that the two things are incompatible, and that therefore the pig- 
ment which appeared in my experiments is due to some factor other 
than the action of light. But it seems to me that, as far as the 
experiments are concerned, all other factors were excluded ; and the 
explanation in the other case seems to be as follows:—I have 
said that the white area on the upper side is an imitation of the 
lower side, and I think that there is probably some peculiar con- 
nection between this area and the lower side, so that it may be 
regarded, in a sense, as an extension of, and continuation of, the 
skin of the lower side. Therefore, so long as the lower side remains 
white, this area of the upper side will also remain white. Possibly, 
if the lower side became pigmented, this white area on the upper 
side would also become pigmented, and it would be a curious ex- 
periment to expose the lower side to the hight, and see if both it and 
the white area on the upper side would develop pigment. 
TV. Growra anp Distrrurion or Youna Foop-risHEs. 
In April, 1893, I had the pleasure of undertaking some experi- 
ments with young flounders for the late Dr. Romanes. I procured 
the specimens as usual from Mr. Dunn, of Mevagissey. They were 
the young of the year in process of metamorphosis, and among 
them I received five young soles a little more advanced in develop- 
ment. I placed these five soles in one of the table tanks in the 
Laboratory, a tank 5 feet long, 24 feet wide, 14 feet deep. When 
received these soles were about 1°5 cm, long, or nearly & inch. 
