136 R BRAITHWAITE ON THE HISTOLOGY OF PLANTS. 



Inulin. — This is only found in the compositge, and most fre- 

 quently in the roots, as in Inulce Helenium, or Elecampane, 

 Helianthus tuherosus, or Girasole Artichoke, Dahlia, Dandelion, &c. 

 In living cells, it only occurs in solution ; but in dead cells, or after 

 drying, it appears in small granules. It is best observed by soak- 

 ing a lump of the root a week or two in alcohol or glycerine, and 

 then, examining a section, the globules are seen to be single or 

 grouped into spherical or hemispherical bodies, often adhering to 

 the cell wall, and traversed by radially divergent cracks ; and after 

 stay in acid, also showing concentric ones. Iodine colours Inulin 

 yellow, and, like starch, it exhibits a black cross by polarized 

 light. 



Aleuron was discovered by Hartig, in 1855, and occurs in the 

 oily seeds of Leguminosie free from starch, in castor oil seeds, the 

 Hazel-nut and Brazil-nut, as well as associated with starch in the 

 albuminous seeds of Conifers as Finns Cemhra, It is in round or 

 elliptic granules, like those of starch, without laminee, and is readily 

 soluble, its reactions shewing that it belongs to the albuminous 

 group. 



Crystalloids. — These resemble crystals in form, but they are 

 of the nature of protein. Hartig and Masche detected them as a 

 nucleus in Aleuron- granules, the latter regarding them as casein. 

 They are found in the Potatoe as small cubes imbedded in pro- 

 toplasm near the nucleus, and Radlkofer detected them in the 

 nucleus of the cells of Lathra3a squamaria ; in the pulp of the fruit 

 of Solanum Americanum, they occur in clusters of violet-coloured 

 rhombic plates. Sol-Iodine colours them fine yellow, Millon's test 

 (nitrate of mercury) deep red. 



Chlorophyl. — The green colouring matter of leaves is widely 

 diffused throughout the vegetable kingdom, and is not contained 

 in Vesicles, but separates from the protoplasm in amorphous 

 granules, or it is deposited around some of the cell-contents, for by 

 the application of alcohol or ether, the chlorophyl is dissolved out, 

 and the substratum is left. Drapaimaldia, Closterium, and other 

 Algae, and also cells of AntJioceros, contain amorphous chlorophyl, 

 invested by the general protoplasm of the cell ; but it is almost 

 always found covering grain-like formations, and the condition is 

 familiarly known as chlorophyl granules. The substratum of these 

 is of two kinds ; 1st, it is formed of a nitrogenous substance, pro- 

 bably hardened protoplasm, which, after removal of the chlorophyl. 



