866 CHANGES OF ORGANIC MATTER IN THti PLAN*. 



plants, notably in seeds, compounds which possess the power of 

 effecting changes in the character of starch, etc. ; but it was not 

 until 1873 that a method was given which enables us to isolate 

 these compounds in a state of comparative purity. This method 

 is based upon their solubility in glycerin, and their ready pre- 

 cipitation from glycerin solutions by means of common alcohol. 1 

 By the use of this method Gorup-Besanez has been able to 

 obtain from the seeds of vetch, flax, etc., a ferment which is 

 soluble in water and glycerin. The substance contains 7.76 per 

 cent of ash constituents and 4.5 per cent of nitrogen. Its solu- 

 tions convert starch into sugar very rapidly at the temperature of 

 20-30 C. ; and in the presence of a dilute acid, for instance 

 hydrochloric, it has the power of peptonizing proteids. In solu- 

 tion, it loses its activity at 80 C. ; but if carefully dried, it can 

 stand a temperature of 120 C. Up to the present time no fer- 

 ment capable of effecting changes in the fats of plants has been 

 isolated. 2 



963. Baranetzky has shown that in the conversion of starch 

 into sugar there are two phases : (1) the formation of dextrin, 

 and (2), at a somewhat higher temperature, the formation of 

 sugar. He observed an acid reaction in the ferment. 



964. In the sap of Carica papaya, Wurtz and Bouchut 8 have 

 isolated a peptonizing ferment which acts promptly upon albu- 

 minoids. The juices of several tropical fruits are said to have 

 the property of softening meats, and this action is regarded as 

 dependent upon some unorganized ferment. 



965. Besides the products already enumerated, there are some 

 bitter and extractive matters and some coloring substances which 

 do not naturally fall into any of the groups described. 



966. From the facts which have now been presented, it is 

 clear that the composition of the sap which escapes from a plant 

 when it is wounded must be very complex. The juices of a 

 plant contain all its dissolved mineral matters, gases in solution, 

 and numerous members of both of the nitrogenous and non- 

 nitrogenous groups already mentioned. 



1 Hufner. Journal fur praktische Chemie, v., 1872, p. 372, and xi., 1875, 

 p. 43. 



* For a short account of the work of Kosmann (Journal de Pharmacie et de 

 Chimie, ser. 4, tome xxii. p. 335) and that of Krauch (Versuchs-Stationen, 

 xxiii. p. 77), see Husemann and Hilger : Die Pflanzenstoffe, I, 1882, p. 238. 



Comptes Rendus, Ixxxix., 1879, p. 425 ; xci., 1880, p. 787. See also the 

 following : Duclaux : Comptes Rendus, xci. p. 731, and Hansen : Sitz. der 

 physikmedicin. Societat zu Erlangen, 1880. 



