CHARACTERISTICS OF PROTOPLASM 3 



many of the metallic salts, by strong acids and alkalies, and by many 

 other chemical substances. 



Under the microscope it is seen almost universally to be granular, the 

 granules consisting of different substances, albuminous, fatty, or carbo- 

 hydrate matter. The granules are not equally distributed throughout the 

 whole cell mass, as they are sometimes absent from the outer part or layer 

 and very numerous in the interior. In addition to granules, protoplasm 

 generally exhibits spaces or vacuoles, usually globular in shape, except- 

 ing during movement, when they may be irregular, and filled with a watery 

 fluid. These vacuoles are more numerous and pronounced in vegetable 

 than in animal cells. Gas bubbles also sometimes exist in cells. 



It is impossible to make any definite statement as to the exact chemical 

 composition of living protoplasm, since the methods of chemical analysis 



FIG. 3. Phases of Ameboid Movement. 



necessarily imply the death of the cell; it is stated, however, that protoplasm 

 contains 75 to 85 per cent, of water, and of the 15 to 25 per cent, of solids the 

 most important part belongs to the class of substances called proteins or al- 

 bumins. Proteins contain the chemical elements carbon, hydrogen, nitrogen, 

 oxygen, sulphur, and phosphorus, the last two in very small quantities only. 

 A protein-like substance, nudein, found in the nuclei of cells, contains phos- 

 phorus in greater abundance. In the cell nucleus a compound of nuclein 

 with protein, called nucleoprotein, forms the most abundant protein sub- 

 stance. Other bodies are frequently found associated with the proteins, such 

 as glycogen, starch, cellulose, which contain the elements carbon, hydrogen, 

 and oxygen, the last two in the proportion to form water, and hence are 

 termed carbohydrates; fatty bodies, containing carbon, hydrogen, and oxygen, 

 but not in proportion to form water; lecithin, a complicated fatty body con- 

 taining phosphorus; cholesterin, a monatomic alcohol; chlorophyll, the color- 

 ing matter of plants; hemoglobin, the complex animal pigment; inorganic 

 salts, particularly the chlorides and phosphates of calcium, sodium, and potas- 

 sium ; ferments, and many special substances. 



The General Physiological Characteristics of Protoplasm. The 

 properties of protoplasm may be well studied in the microscopic animal called 

 the ameba, a unicellular organism found chiefly in fresh water. These 

 properties may be conveniently studied under the following heads: 



The Power of Spontaneous Movement. When an ameba is observed 

 with a high power of the microscope, it is found to consist of an irregular mass 



