644 EXPERIMENT STATION RECORD. 



(3) Inulin, w(CyH„)0,-,)/ plays a similar role in tbe Coinpositfe to 

 starch in most other plants. It is not stored up in grains like starch, 

 but occurs in solution. By immersing parts of the plant in alcohol the 

 inulin is changed to a crystalline state. Inulin further differs from 

 starch in yielding levulose by hydrolysis with dilute acids instead of 

 dextrose. 



There is also a class of substances accompanying inulin and yielding 

 levulose, to which belong a series of gummy materials precipitated by 

 alcohol and of nearly the same composition as inulin, which occur with 

 the latter in the tubers of HeUanthus tuberosus. These are levulin and 

 synanthrose, which, according to recent investigations by Tanret, are 

 produced from pseudo inulin, inulenin, helianthenin, and synanthrin. 

 To tliis group belong also a large uumber of substances from various 

 plants, partly Oompositie, all of which are amor])hous, levorotatory, 

 and the larger part of which at least yield levulose on hydrolysis. 

 Among these may be mentioned levosin, triticin, irisin, sinistrin, scillin, 

 phlein, graminin. etc. 



(4) Mtmnose-yieldinff substances or mannans. — According to the inves- 

 tigations of Reiss and of E. Fischer, many seeds with a hard endo- 

 sperm composed of thick-walled cells contain an amorphous substance 

 which, on heating with dilute acids, yields nuiunose. This substance, 

 was first isolated by Keiss and was named seminin. It is at present 

 called mannan, or when it is insoluble in water and in dilute potassium 

 hydroxid, paramannan. Tlie latter (paramannan) occurs in the hard 

 seeds of dates, the coffee beau, iStryehjios nux-vomica, etc., and espe- 

 cially in vegetable ivory. More soluble mannan is contained in the roots 

 of salep and in several Japanese plants. Wood also contains some 

 mannan. 



(5) Galaetose-yielcUng substances or gaJactans are gum-like substances, 

 occurring especially in leguminous plants, and yielding galactose by 

 hydrolysis and by oxidation with nitric acid the same product as galac- 

 tose, i. e., mucic acid. These galactans are in part soluble in water and 

 very dilute potassium hydroxid, and in part insoluble in the latter. The 

 soluble substances are designated a, fi, and (^-galactan, and the insolu- 

 ble substances, paragalactans. Miintz, and E. Schulze, Steigor and 

 Maxwell have studied the different galactans in lupine seed, peas, beans, 

 etc., and named one of the soluble galactans in lupine, lupeose. Other 

 chemists have isolated galactans from agar-agar, etc. 



(6) Mucilages and gums. — Pectin substances occur to considerable 

 extent in plants, for example, in the beet, berries of different kinds, 

 flaxseed, etc. They gelatinize with water, giving ai thick and some 

 times stringy or slimy solution, and on inversion with dilute mineral 

 acids yield the different glucoses described above and also i)entoses 

 (see below). For the most part they are carbohydrates, and they all 

 belong to the nitrogen-free extract. 



'The iuulin molecule appears not to be aa large as that of starch, and the value of 

 " It" lias recently been stated at 12 and 18. 



