MlTAllol.ISM 1\ LIVING PLANTS. 



457 



Of the various soi'ts of liuiMin^' inatei-ials, the albumens must first be con- 

 siilerod; tliey are to be reclvoned as tiie most important constituents of living 

 protoplasm. Although their chemical composition has not as yet been ascertained 

 with complete cert^iiuty, it is known that, besides the carbohydrate constituents, 

 albumens contain nitrogen and OS-l-T per cent of sulphur; that carbon with 



Fig. 123.— Crystals and Cryetalloids. 



I Vertical section through a fallen leaf of the Virginian Creeper (Ampelopsis hederacea). In some of the cells are clustered- 

 crystala, in others bundles of needle-shaped crystals (raphides); iu one cell there is a single envelope-shaped crystal. 

 ^^-* Solitary and clustered crystals an<l raphides of oxalate of lime ; more highly magnified. ^ Sphere-crystals in the 

 interior of a swollen bladder-like hypha, with small clustered cryst-als ou the outer side of the hyphal thread ; from 

 Phalltu eaninus. ' A single needle from a bundle of raphides. « Section of a portion of a Potato-tuber with crystalloiiis 

 and starch-grains iu its cells. « Crystalloiiis in the cells of a gland on a Potato-leaf, lo-l-j Crystalloids in aleurone grains. 

 '*. 1* Globolda in aleurone grains >^ ^i^ Isolated crystalloids. io-i« From the seed of Jticinvs communU ; very highly 

 magnifled. 



many, perhaps with more than a hundred, atoms takes part in the construction 

 of a molecule, and that consequently the molecules of albumen are very large. 

 In order that a carbohydrate may become transformed into an albuminous body, 

 nitrogen and sulphur, at any rate, must be drawn into the combination. Nitrogen 



