Germination of the Seed of the Castoi^oil Plant. 381. 



Sachs* held that, as the cells of the cotyledons of Jticinus contain oil 

 after germination has commenced, this oil must have the power of 

 passing through cell walls, and even through the epidermis of the 

 cotyledons. 



Detmer,f on the other hand, suggests that, like starch, it becomes 

 a material capable of dialysis, and travels by such means, the oil 

 which appears in the cotyledons and other parts being due to a 

 re-formation at the spot at which it is found, as is the case with 

 transitory starch. 



The structure of the cotyledon shows that the actual passage of 

 oil into it would be a matter of very great difficulty. Its outer 

 epidermis is separated from the cells of the endosperm by a very 

 thick layer of cell walls, the remains of cells whose contents have 

 been absorbed ; and microscopic examination of this layer while 

 absorption is proceeding fails to detect any fat in its thickness. All- 

 analogy points too to dialysis as the mode of absorption, and the 

 forms in which the reserve material* are to be found in the endosperm 

 during germination indicate such a process as the probable one. 



Of the various bodies found, sugar and the crystallisable acid are 

 easily capable of dialysis, and are obtainable from the cotyledons. 

 Peptone also can pass through a membrane. Asparagiu can be 

 detected on the cotyledonary side, but not in the endosperm. Peptone, 

 however, is not to be detected in the cotyledons. 



Besides these, there are to be found in the young plant a certain 

 amount of oil, some considerable quantity of starch, and a trace of 

 fatty acid. 



The form of absorption of the nitrogenous matter seems to he 

 that of asparagin, for peptone, though formed, does not seem to 

 leave the endosperm. This is in accordance with the condition in 

 the lupin, J where the nitrogenous matter travels in the same way, 

 peptone being only a stage in its formation. The fact that asparagin 

 is not traceable in the endosperm is not a valid objection to this 

 view, for it is quite possible that it is absorbed as fast as formed, or 

 that so little is left behind that it escapes observation. 



Detmer's hypothesis seems to account satisfactorily for the appear- 

 ance of the oil in the young plant, and, if valid, it explains also the 

 trace of fatty acid there. The latter could only be explained other- 

 wise by its having, either in the free state, or in the form of one of 

 its salts, the power of dialysis. Experiments already recorded 

 negative the idea of its dialysing in the free state. Some careful 

 investigations were made as to the behaviour of its alkaline salts. 

 fcome ricinoleic acid was made into soaps with different strengths of 



* Op. cit., p. 347. 

 t Op. cit., p. 370. 

 J Green, op. cit. 



