4 Marshall Ward and Dunlop. 
the seeds and the endocarp. The chief difficulty here was 
to obtain perfectly clean portions. It was easy to separate 
the endocarp ; far less easy to separate the testa of the seed 
from the contents. The large yellow embryos slip out pretty 
easily. I doubt whether the testa was ever got perfectly free 
from the nucellus in these earlier trials. A decoction of the 
freed outer pericarps was then made, and the clear yellow 
filtered solution placed in test-tubes and treated as follows : — 
A : was left alone. 
B : testa was added. 
C : endocarp was added. 
D : endosperm was added. 
E : embryo was added. 
All the experimental tubes were placed in a warm chamber 
and kept at 35°C. After half-an-hour I found a copious 
yellow crystalline precipitate falling in B, and faint traces of 
a similar precipitate in E. In all the other tubes the liquid 
was still clear. After eight to twelve hours traces of a pre- 
cipitate were observable in the other tubes, but it was more 
than a day after that any noteworthy changes were observable. 
Evidently something in the testa (and possibly in the 
embryo also) acts as a ferment on the yellow glucoside in 
the pericarp. I repeated the experiment B, but boiled the 
solution after adding the testa ; a coarse cloudy precipitate 
formed. It became probable later that this was due to the 
boiling. I again repeated experiment B, with the following 
modifications. In one case I employed a glycerine-extract of 
the testa ; this was effectual, as before. In another case I 
used a filtered water-extract of the testa ; this was effectual 
also, but not so if boiled first. There seemed to be a soluble 
ferment in the testa of the seed then, and it is obvious that 
the results confirmed previous experiments. 
It was now time to examine the tissues histologically, and 
I confined my attention at first to the testa and pericarp. 
In the cells of the outer pericarp are brittle waxy yellow 
masses (Fig. 6), which dissolve at once in water, and are 
evidently masses of the glucoside (xanthorhamnin). The 
