1905.] On the Germination of Seeds of the Castor Oil Plant. 71 



As this change supervenes upon the development of an acid reaction in 

 the seeds, it seems not unlikely that it may be caused by the action of the 

 organic acid which is formed in the cells of the endosperm almost as soon 

 as germination begins. 



On resuming the work a more careful examination of the oily contents 

 of the endosperm cells led to the discovery that they contained, mixed with 

 the oil, a certain quantity of a substance, the decomposition products of 

 which pointed to its being a lecithin (a peculiar fatty body containing 

 phosphorus). The resting seeds were pounded in a mortar till they formed 

 a homogeneous paste. This was extracted for some hours with ether in 

 a Soxhlet's apparatus, and was afterwards twice extracted further on a 

 water-bath with absolute alcohol, the flask being fitted with a reflux con- 

 denser. The alcoholic and ethereal extracts were mixed and evaporated 

 to dryness at a gentle heat on a water-bath, and the fatty residue fused with 

 dry carbonate and nitrate of potassium until all trace of free carbon had 

 disappeared. After cooling, the fused residue was dissolved in water, and 

 the addition of ammonium molybdate and nitric acid produced a yellow 

 precipitate, indicating the presence of phosphorus. The quantity of the 

 latter was ascertained by converting it into magnesium pyrophosphate and 

 weighing. 



A little of the oil was then hydrolysed by boiling with baryta, when 

 there separated out a flocculent precipitate of a barium salt, which, after 

 washing and drying, was found to contain no phosphorus. This barium salt 

 had the characteristic soapy appearance of the stearates. It was found 

 possible to identify cholin in the endosperm of the germinating seeds, as will 

 be more fully shown a little later (p. 74). 



The only way of estimating the amount of the lecithin present in the 

 alcohol-ether extracts of the endosperm was to determine accurately the 

 phosphorus as magnesium pyrophosphate. Great precautions were taken 

 to ensure the repeated use of very dry ether so as to exclude the possibility 

 of extracting any inorganic phosphates. A little of the oily residue from 

 the extraction was incinerated in a platinum dish, and it was found to leave 

 no inorganic ash. We therefore assumed that all the phosphorus extracted 

 as described was originally present in the complex lecithin form. Taking 

 the formula usually given for lecithin (C44H90NPO4), we calculated the 

 amount of the latter that would be present. Its average amount was equal 

 to - 236 per cent, of the dry weight of the seeds. 



Several series of experiments were made to investigate the changes in the 

 fatty constituents of the endosperm during germination. The action of 

 the fat -splitting enzyme known now as lipase was confirmed, and the early 



