Thi Seed and ils Germination. 
509 
solution, glycerine, or any other neutral solvent, is found to be 
quite inert towards proteids, and an extract of the resting seed of 
the castor-oil plant cannot decompose the oil. The ferments, 
in other words, do not make their appearance till germination 
begins, and the commencement of this process is really dependent 
on their development. From what, then, do they arise ? 
The condition of things is more easily ascertained in the 
resting castor-oil seed than in that of the lupin. If an extract 
of this seed, found on experiment to be quite inert, be warmed 
for an hour or two with a little very weak acid, the ferment 
power makes its appearance in the solution. Again, if the 
seeds be extracted at a temperature of about 8G° to 104° 
Fahrenheit by a faintly acid solution of this kind, an active 
preparation is at once obtained. The ferment is in the cells of 
the seed, but not in an active condition. To put it in other 
words, the seed before germination contains in its cells some- 
thing which, though not the active ferment, can be readily 
transformed into it by warming with a little weak acid. To 
this something, which can be extracted from the resting seed as 
easily as the ferment can be from the germinating one, the 
name " mother of ferment," or zymogen, has been given. The 
resting seed, therefore, differs from the germinating one in 
containing zymogen instead of ferment, and the onset of ger- 
mination is brought about by the conversion of the former into 
the latter. To the conditions to which the seed is exposed 
when sown we must look for the explanation of this conversion. 
The reaction of the resting seed is neutral, that is, it is neither 
acid nor alkaline, whilst the contents of the cells are dry. The 
earth in which it is sown is moist, and water is soon absorbed 
by it. This absorption of water is a necessary antecedent to 
germination. Water gaining access to the cells sets up changes 
in the living substance, in consequence of which certain vege- 
table acids are formed. The change in the reaction of the seed 
from neutral to faintly acid can be easily seen. The vegetable 
acids so formed convert the zymogen present in the cells into 
the active ferment, and at once the conversion and transporta- 
tion of the nutritive materials towards the seats of growth or of 
absorption set in. 
In these various ways, then, the young embryo is fed. The 
(reserve materials are in all cases transformed from the insoluble 
indiffusible condition in which they are deposited into soluble 
diffusible forms that enter its tissues in order to enable the 
embryo to proceed in its development. Their further fate is to 
undergo changes of a reverse order, the living substance growing 
and increasing in amount thereby. This process, constituting 
