503 
The Seed and, its Germination. 
by a living endosperm. In the exalbuminous seeds tlie enibrvo 
absoi'bs the contents of the endosperm before the resting period, 
and the endosperm disappears. In the case of the barley the 
endosperm cells fill themselves with starch and other product-!, 
but this is their last effort. The endosperm of the castor-oil 
plant accumulates aleurone grains and oil in its cells, but after 
the period of rest it can resume the activity which it possessed 
before, and initiate the changes of germination. The living 
substance thus remains in these cells in a condition which it 
does not maintain in the cells of the barley, where active life, 
when germination commences, is confined to the embryo, which 
secretes the ferments in the cells forming the epithelium or 
coating of the scutellum. This activity still residing in the 
protoplasm of the endosperm of the castor-oil seed explains the 
later stages in its germination. The ferments are formed in the 
matrix of protoplasm ; by one of them the oil is decomposed into 
fatty acids and glycerine. Besides giving rise to the ferments, 
the protoplasm is the seat of other chemical activity, processes of 
gentle oxidation and reduction taking place there as long as it is 
living. By such processes the fatty acid and the glycerine are 
transformed into the crystalline acid and the sugar. The barley 
grain, then, contains a living embryo surrounded by a store of 
reserve food materials, which can be called into the nutritive 
processes only by the action of the embryo, which has, in fact, 
to secrete the ferments necessary for the digestive processes. 
The castor-oil bean contains a living embryo, but the surround- 
ing tissue of the endosperm not only stores the food for it, but 
retains the power of transforming that food into the forms 
needed by the embryo, and supplies it ready for absorption. 
By the action of the ferment it splits up the fat or oil ; by the 
further activity of the protoplasm of the cells it transforms the 
fatty acid and glycerine into an acid and a sugar which are 
capable of passing through the walls of the cotyledon and so 
entering the young plant. 
These changes comprised in germination are set up only 
when the seed is exposed to moisture and warmth. Why is it 
necessary thus to wait? Why should not the changes in the 
reserve materials follow at once on the maturity of the seed, and 
so cause the growth to go on without any resting period ? The 
answer to this turns on the condition of the ferments in- the 
resting seed. If these were in an active condition there, as they 
are in the germinating seed, there would seem to be no reason for 
the suspension of activity. But an extract of the seeds of the 
lupin before germination begins, whether made with water, salt 
