98 



reliable analytical method must first be pgreed upon, and even 

 then a more scientific method of valuing hops will also be 

 necessary. 



However, in respect to the part played by tannic acid in the hop 

 plant, BECKENHAUPT has made some remarkable observations. He 

 says in regard to the proportion of tannin (Petit Journal du Brasseur, 

 1903, p. 6 1 8) that it appears to correspond to a red colouration of 

 the stalks, a colouration which characterises early hops. This colour 

 must be attributed to the presence of anthocyanine, a substance in 

 which KEENER thinks he distinguishes a protection for the protoplasm 

 against too strong a light, and also a means of transforming the 

 light rays into heat rays. It seems clear that anthocyanine protects 

 the plant at the beginning of its vegetative career against inclement 

 weather, and it is possible that it also protects the new-formed 

 chlorophyll against the absorption of yellow rays. It is very interest- 

 ing to remark that DENNERT considers this anthocyanine to be a 

 derivative or product of the transformation of tannin, and by plunging 

 green stalks of the hop into a solution of tannic acid, BECKENHAUPT 

 has obtained a weak but undoubted colouration of anthocyanine. 

 Also by the action of potassium carbonate on tannin solution the 

 same colouration is obtained. This relationship, he says, between 

 tannin and anthocyanine in early hops serves to explain the presence 

 of large quantities of tannin in the cones, and at the same time is 

 useful in appreciating the constitution of each variety, for there is 

 no doubt that it is the tannin which has allowed the young hops 

 to develop when placed under unfavourable food conditions. The 

 plant requires certain organs to protect it against wet, mould, 

 animals, and insects, but the means of defence vary according to the 

 situation and dangers present, and the conditions under which the 

 plant has to develop. There is reason to think that the lupulin or 

 the resins protect it against premature wet, at the same time that the 

 bitter acids and the strongly smelling essential oil protect it against 

 insects and birds which would devour it. It is the tannin, on the 

 other hand, which appears to prevent the cone from prematurely 

 falling to pieces. One knows that the cones which develop freely, 

 and which naturally contain much nitrogen, disintegrate readily; 

 frequently it is sufficient only to shake the plant to cause them to 



