246 PLANT AND ORGANIC CHEMISTRY 



A typical living cell may be described as composed of a cell 

 wall and contents. The cell wall is a firm, elastic membrane, 

 closed on all sides, and consists mainly of cellulose, water, and 

 inorganic constituents. The contents consist of a semi-fluid 

 colloidal substance, lying in contact with the inner surface of 

 the membrane, and like it, closed on all sides. This always is 

 composed of albuminous substances. In the higher plants, at 

 least, a nucleus occurs embedded in it. A watery liquid holding 

 salts and saccharine substances in solution, fills the space called 

 the vacuole enclosed by the protoplasm. 



These simple plants may be seen as actively moving cells or 

 as non-motile cells. The former consist of a minute mass of 

 protoplasm, granular and mostly colored green, but clear and 

 colorless at the more pointed end, and where it is prolonged into 

 two delicate filaments called cilia. After moving actively for a 

 time they come to rest, acquire a spherical form, and invest 

 themselves with a firm membrane of cellulose. This firm, outer 

 membrane of the Prolococcus accompanies a higher differenti- 

 ation of tissue and localization of function than is found in the 

 plasmodium. 



H&atococcus and plasmodium come under the classes Algae 

 and Fungi of the Thallophyta group. The division * of this 

 group into two classes is based upon the presence of chlorophyll 

 in Algae and its absence in Fungi. Gelatinous starch is found 

 in the Algae; the Fungi contain a starchy substance called 

 glycogen, which also occurs in the liver and muscles of animals. 

 Structureless bodies, as athalium, contain no true sugar. Strati- 

 fied starch 2 first appears in the Phanerogams. Alkaloids have 

 been found in Fungi, and owe their presence doubtless to the 

 richness of these plants in nitrogenous bodies. 



In addition to the green coloring- matter in Algae are found 

 other coloring- matters. 3 The nature 4 of these coloring- mat- 



1 Botany, Prantl and Vines, London, 1886, p. no. 



2 For the literature of starch, see p. 115, Die Pflanzenstoffe, von Hilger and 

 Husemann. 



3 Kiltzing, Arch. Pharm. xli, 38. Kraus and Millardet, Bui. Soc. Sciences 

 Nat., Strasbourg, 1868, 22. Sorby, Jour. Lin. Soc. xv, 34. J. Reinke, Jahrb. 

 Wissenscht. Botan., x, B. 399. Phipson, Phar. Jour. Trans., clxii, 479. 



4 Prantl and Vines, p. in. 



