CHARACTERISTICS OF PROTOPLASM 3 



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 

 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, nuclein, found in the nuclei of cells, contains phos- 

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



FIG. 3. Phases of Ameboid Movement. 



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; inorganic salts, particularly the chlorides and phos- 

 phates of calcium, sodium, and potassium; ferments, and many special 

 substances. 



The 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 proper- 

 ties 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 

 of protoplasm containing one or more nuclei, the protoplasm itself being 

 more or less granular and vacuolated. If watched for a minute or two, an 

 irregular projection is seen to be gradually thrust out from the main body; 

 other masses are then protruded until gradually the whole protoplasmic sub- 

 stance is, as it were, drawn over to a new position, and when this is repeated 



