Thiselton-Dyer . — Morphological Notes. 151 
been no external supply available. It is well known that the 
placental tissues in the melon break down into a copious 
sugary juice as the fruit ripens, and upon this it is perfectly 
clear that the young seedlings fed. This is not surprising in 
view of the well-known research of E. Hamilton Acton 1 . 
What is, however, more remarkable is that they were able to 
plunge their roots into the fairly resistent and less dis- 
integrated tissues of the pericarp itself. This penetration is 
clearly shown in the lower part of the section on Plate VIII. 
The cotyledons of the seedlings were, as stated by 
Mr. Horace Brown, distinctly green. He wrote to me: — 
‘ I think the amount of chlorophyll present must be very 
small. It does not give a strong coloration to the alcohol in 
which the plants are immersed, and what little green there is 
fades rapidly on exposure to light.’ 
Subsequently he wrote to me further : — 
‘ I amused myself by scooping the seeds out of a melon 
and testing the translucency of the walls of the pericarp. 
I was quite surprised to find how much light would pass 
through fully ij in. of the walls. In full sunshine there must 
be quite a respectable twilight in the neighbourhood of the 
seeds, and as I see Van Tieghem states that the formation of 
chlorophyll in etiolated seedlings commences in a diffused 
light which will barely permit small print to be read by the 
eye, we need not wonder that the ovarian seedlings contained 
a small amount of chlorophyll.’ 
Chlorophyll is formed in the cotyledons of Conifers in 
complete darkness 2 as well as in the precocious germination 
of seeds of the orange, which occasionally occurs. Such cases 
are, however, quite exceptional. 
Whether the small amount of chlorophyll present in the 
melon seedlings was effective functionally to an appreciable 
extent may be doubted. The chemical changes which took 
place in the interior of the fruit would be accompanied by the 
evolution of carbonic acid, which would probably be present 
1 Proc. R. S., Vol. xlvii, pp. 1 50-1 75. 
2 Sachs, Textbook, second ed., p. 743. 
