THE CIIEMISTKY OF FRUIT RIPENING. 139 



strychnine an(] other poisonous allcaloid?^, while tlie juicy pulp is but very slightly 

 impregnated with these bitter poisons (Fluckiger and I [anbury, riiarniaco- 

 graphia, p. 381). Tlie seeds of henbane, and stramnioniuin, ami tiie calabar 

 beau contain potent alkaloids. The unripe tomato often contains traces of 

 solanine, a poisonous alkaloid, which disap))ears during ri[)ening, probably by a 

 glucosic fermentation. The same alkaloid is sometimes found in the green or 

 exposed parts of potato tubers. 



Many of the vegetable alkaloids are stable compounds, having clearly marked 

 chemical characteristics. Some of the opium alkaloids closely resemble others, 

 in their comjiosition. Different species of the same family often yield the same 

 alkaloids. The theobromine of the chocolate nut can be changed by the 

 chemist into caffeine, the alkaloid of the coffee berry. Such an insight has been 

 obtained of the structure of conine, the alkaloid of the classic poison -hemlock, 

 that it has been formed from inorganic materials, through the processes of the 

 laboratory. But no evidence has been obtained as to the steps through which 

 alkaloids are formed in the living plants. 



It is little enough we know of the productive chemistry of plants. As, at the 

 beginning, wo had need to plead ignorance of plant constituents, still more, at 

 the end of our brief survey, must we declare ignorance of the chemical genesis 

 of those constituents. AVc can only obtain such glimpses of the progressive 

 order of plant chemistry, and we have only such a distant view of chemical 

 action itself, as can give us some hints of the order, and harmony, and grandeur 

 of the molecular changes going on in ripening fruits before us. None the less 

 for our ignorance, the forces each season complete their work and drop their 

 bountiful products into our hands, 



Um'versiti/ of Michigan, July 31, 1877. 



