Germination of the Seed of the Castot'- oil Plant. 373 



from cell to cell has also remained unexplained, except by Sachs's 

 first hypothesis of their ultimate conversion through the form of 

 starch into sugar, and by a suggestion he makes that some of the oil 

 at least passes as such through the cell walls of the endosperm into 

 the cotyledon. 



In taking up the subject where it had thus been left by previous 

 investigators, and endeavouring to throw further light on the several 

 steps that had been established by them, I commenced to work upon 

 the seed of the castor-oil plant (Ricinus communis), and I set before 

 me the following problems : 



1st. By what agencies are the reserve materials made available for 



the nutrition of the embryo ? 

 2nd. In what condition and by what process do they undergo 



absorption ? 

 3rd. What parts are played in the process of germination by the 



endosperm and by the embryo respectively ? 



I selected Ricinus as the material to work upon, because the con- 

 tents of the seed have been accurately ascertained, and found to 

 contain a large quantity of oil ; and because the process of germination 

 is not prolonged. A few of the points that arose during the work I 

 also investigated on the seed of the cocoanut palm (Cocos nucifera). 



The seeds of the castor-oil plant consist of a central embryo, 

 embedded in a mass of endosperm, the whole incased by a hard testa. 

 The tnicropyle is protected by a well-developed caruncle. A section 

 of the endosperm shows the cells to be nearly filled with oil, which 

 exudes on pressing the bruised seed. This oil can be removed by 

 solvents, when the cells are found to contain also stores of proteid in 

 the forte of alenrone grains embedded in protoplasm, the grains con- 

 taining each a crystalloid of proteid and a small aggregation of 

 mineral matter. Starch is not present, nor is more than a trace of 

 sugar to be found, and this small amount is not constant. There is 

 no great amount of cellulose, the cell walls being very thin and the 

 cells of fair size. No glucoside can be detected in the cells. 



The amount of oil to be found is stated differently by different 

 observers. According to Harz,* the quantity varies from 40 to 

 68 per cent., the highest figure being quoted by Cloez. Blumenbach 

 puts it at 50 per cent. I found a fair sample of the seeds to yield 

 58 per cent, of their dry weight. The oil is somewhat complex, 

 yielding, on saponiKcation, according to Lecanu and Buffy,f three 

 fatty acids, ricinstearic, ricinic, and ricinoleic, of which the latter 

 is the most abundant. It has the composition represented by the 

 formula CjgH^C^. 



* ' Landwirthsch. Samenkunde,' 1885, p. 836. 



f Harz, ' Landwirthsch. Samenkunde,' 188^ p. 836. 



