CHAP, vi The Metabolic Processes 389 



them as the pollen-tubes increased in length during germina- 

 tion. In neither case could a plastid be detected. In the 

 styles of various species of Lilium minute specks of starch 

 appear as the flower matures, extremely small, and in 

 exceedingly large numbers. No plastids can be found in 

 the cells. It appears, therefore, that the ordinary cyto- 

 plasm can form starch without such differentiation. 



(b) Glycogen. This substance, which appears to play the 

 part of a reserve material in the animal organism, is met 

 with occasionally in plants, but its distribution is almost, 

 if not entirely, confined to thallophytic forms. It was 

 first observed in vegetable protoplasm by Kiihne, who, in 

 1868, demonstrated its presence in the plasmodium of 

 Aethalium. It was observed in the same situation in 1881 

 by Reinke and Rodewald, who found 4-7 per cent, of the 

 plasmodium consisted of it. After that period its oc- 

 currence in various thallophytic forms, both algal and 

 fungal, was demonstrated by many observers, chief among 

 whom have been Errera and his pupil Clautriau. Their 

 memoirs appeared in 1882 and 1885, and in 1895, respec- 

 tively. The writings of the last fifteen years of the century 

 showed a very wide distribution of glycogen among the 

 Fungi ; among the Algae it was found most prominent in 

 the Cyanophyceae, and apparently absent from the Phaeo- 

 phyceae and Rhodophyceae. Errera found a substance 

 resembling glycogen in Linum usitatissimum, Mahonia 

 repens, and Solanum tuberosum, but he hesitated to identify 

 it as such. 



(c) Inulin. The occurrence of inulin in solution in the 

 cells of the vegetative tissues of a well-known group of the 

 Compositae and their allies was established in the early 

 part of the nineteenth century. Sachs appears to have 

 been the first to observe its separation in the form of 

 sphere crystals after appropriate treatment with alcohol. 

 But little attention to the question of its deposition has 



