1905.] On the Germination of Seeds of the Castor Oil Plant. 



73 



Lecithin has been shown by Overton * to be a normal constituent of living 

 cells, and to exercise considerable influence on the transport of various 

 materials across the limiting layers of the protoplasm. It has no doubt also 

 a certain, though at present undetermined, nutritive value. 



The composition of lecithin is indicated by the change which it undergoes 

 on hydrolysis, when it is decomposed into stearic (or palmitic or oleic) acid, 

 glycero-phosphoric acid and cholin. 



C 44 H 90 NPO 9 + 3H 2 = 2C 18 H 36 2 + C 3 H 9 P0 6 + C 5 H 15 N0 2 . 



Lecithin. Stearic acid. Glycero- Cholin. 



phosphoric 

 acid. 



From this, its constitution has been represented as 



/OCOC 17 H 3 5 

 C 3 H 5 f OCOC 17 H 35 



\0 - PO(HO)0(CH 2 ) 2 N(CH 3 ) 3 OH 



Only a trace of it exists in the resting seed ; as it increases during 

 germination and the quantity remains fairly constant during the whole 

 period of absorption of the fatty reserves by the seedling, we have evidence 

 of a formation of it during the germinative processes. The endosperm 

 contains such substances as may yield the several groups necessary for its 

 formation. The decomposition of the oil by the enzyme lipase can furnish 

 the fatty component, belonging to the oleic group, and at the same time the 

 glycerine of the glycero-phosphoric acid. The phosphorus of the latter is at 

 hand in the shape of the phosphatic globoids whose solution has already been 

 alluded to. The [nitrogenous body cholin may be looked for among the 

 products of the decomposition of the proteids of the aleurone grains. 



Examination of the contents of the endosperms during germination 

 ultimately established the presence of all these constituents. The fatty 

 acids and the glycerine were identified in 1888, and the methods of detection 

 and estimation were quoted in the former paper. A careful examination of 

 the phosphates of the globoids, taken for purposes of comparison from seeds 

 at the respective stages of germination quoted in Table A (p. 72) showed that 

 their solution proceeded side by side with that of the oil. 



No change in them could be observed under the microscope till the testa 

 was cracking, and the time of its inception varied a good deal. In the early 

 stages, prior to such cracking, no reaction for phosphorus could be obtained 

 from a watery extract. The quantity of phosphorus present in the resting 

 seed was 0*205 per cent, of the dry weight ; this diminished in Stages 2, 3, 

 and 4 of Table A to 0'16, 0*14, and O'll per cent. The globoids are decom- 



* Overton, ' Pringsheim's Jahrb.,' vol. 39 (1900). 



