5 
On the Fruits and Seeds of Rhamnus. 
testa contains thick- walled pitted cells (Figs. 4 and 12) which 
contain a peculiar finely granular substance, which dissolves 
at once on adding water and disappears. I was for some 
time strongly inclined to regard this fine grey powder as the 
ferment with which we had been experimenting. To test the 
accuracy of this conclusion I made very thin sections of the 
dry testa, and placed them directly into solutions of the 
glucoside from the pericarp ; the sections were from all parts 
of the testa. In less than half-an-hour I found a semi- 
crystalline precipitate resembling the precipitates of rhamnin 
obtained in the test-tubes. 
I then asked Mr. John Dunlop, who was at that time 
working in my laboratory at the Owens College, to go over 
the anatomy and histology of the fruits and seeds of Rhamnus 
with me ; this he was good enough to do, and most of the 
figures in the plates are due to his pencil. We confined our 
attention to Rhamnus infectorius at the time ; later on I 
examined the histology of several other species. 
The fruit of Rhamnus infectorius is a berry-like drupe 
(Fig. 1) with a dry waxy outer pericarp, and a thin woody 
endocarp : within this are three or four erect seeds, which, if 
separately and completely enclosed in the sclerenchymatous 
endocarp, might almost be called nutlets (Fig. 2). A hori- 
zontal transverse section made equatorially across the drupe 
reveals the seeds lying loosely in the loculi of the dry fruit, 
one in each loculus, enclosed in the hard thin endocarp. On 
splitting this endocarp the seeds fall out, being loose within 
it ; each seed is smooth and shining, brown in colour, and 
with a longitudinal deep groove on the dorsal side. A trans- 
verse section of the seed shows a hard brown testa, doubled 
in at the dorsal groove (Figs. 3 and 21), the margins of the 
groove being thickened and harder than the rest. The 
cavity within the testa is nearly horseshoe-shaped in trans- 
verse section, and filled with white endosperm, in which lie the 
cotyledons : these are face to face and also horseshoe-shaped 
in transverse section. Between the endosperm and testa were 
several rows of broken down and disorganised cells, evidently 
