2 4 6 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 Proiococcus accompanies a higher differenti¬ 
ation of tissue and localization of function than is found in the 
plasmodium. 
Haatococcus and plasmodium come under the classes Algae 
and Fungi of the Thallophyta group. The division 1 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 Kützing, 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. m. 
