THE STOEAGE OF EESEEVE MATEEIALS 245 



During germination it splits up into benzoyl aldehyde, 

 hydrocyanic (prussic) acid, and grape-sugar. Many such 

 bodies are known, and they are somewhat widely distri- 

 buted. Some occur in seeds, but they are more frequently 

 represented in the reservoirs contained in fleshy roots and 

 stems. Many plants belonging to the Cruciferce and several 

 allied orders are particularly rich in reserve materials belong- 

 ing to this group. Sinigrin, or myronate of potash, is the 

 principal glucoside which they contain. It splits up into 

 sulphocyanate of allyl, grape-sugar, and hydrogen-potassium- 

 sulphate. 



The nutritive value of these bodies is partly due to the 

 sugar which they yield on decomposition. The evidence 

 that the other products can minister to nutrition is not 

 very complete, though it seems satisfactory in certain 

 cases. 



Fats or oils are frequently stored as reserve food-stuffs 

 in different plants. The distribution of this material is 

 very varied, though, as in so many other cases, the seed is 

 the most general place of deposition. Many seeds that 

 for instance of the castor-oil plant contain as much as 

 60 per cent, of their dry weight of oil, which is non-volatile. 

 Others contain as little as 2 per cent., and between 

 these limits very varying amounts may be found. When 

 the oil is in great preponderance, it is usual for no other 

 form of carbonaceous reserve to be present ; in cases where 

 but little oil occurs starch is usually found as well, as in so 

 many of the Leguminosce. The Cruciferce as a group often 

 contain oil in fairly large quantity. As a rule nitrogenous 

 reserves in the shape of aleurone grains accompany the oil. 



In other places than seeds large deposits of oil often 

 occur, though their purpose is not so obvious. We have 

 them in large amount in the pericarps of certain fruits, 

 such as the olive ; in the petals of many flowers, e.g. Funkia 

 and Ornithogalum ; in the leaves of some of the Agaves, the 

 roots of Oncidium, &c. They can hardly be regarded in 

 some cases as truly reserve materials, being perhaps more 



