68 THE POPULAR SCIENCE MONTHLY. 



surface of the body is touched with the point of a pin, or with another 

 body producing a chemical alteration, as for examj)le a small drop of 

 acid, or when a current of electricity is passed through it, the threads 

 are drawn in, and the entire body contracts into the form of a spheri- 

 cal lump. The same threads perform also the function of providing 

 alimentation. 



When a small infusorium or any other nutritive particle comes acci- 

 dentally in contact with the extended pseudopodia, these run quickly 

 over it like a fluid, wind around it with their numerous little branches, 

 fuse into one, and press it into tlie interior of the body, where all the 

 nutritive portions are rapidly absorbed and immediately assimilated, 

 while all that is useless is quickly ejected. 



The variations among the diiferent moners, of which so far sixteen 

 kinds have been described (Haeckel's "Monographic cler Moneren)," 

 consist partly in the various forms of the pseudopodia, but especially in 

 the diflerent kinds of propagation. Some of them merely divide into 

 halves on reaching a certain size ; others put forth little buds which 

 gradually separate from them ; and others experience a sudden divi- 

 sion of the mass into numerous small spherical bodies, each of which 

 instantly begins a separate existence and gradually reaches the size 

 of the ancestral organism. 



The chemical examination of the homogeneous protoplasmic body 

 shows that it consists throughout of an albuminous or slime-like mass, 

 hence of that azotic carbonate of the character of the highly-com- 

 pounded connective group called proteine, albuminoids, or plasson 

 bodies. Like other chemical compounds of this group, protojjlasm 

 exhibits several reactions which distinguish it from all others. It is 

 easy to detect it under the microscope, on account of the facility with 

 which it combines with certain coloring matters, as carmine and ani- 

 line ; it is colored dark yellow or yellowish brown by iodine and nitric 

 acid; and it is coagulated by alcohol and mineral acids, as well as by 

 heat. The quantitative composition of protoj^lasm, though in some 

 cases greatly varying, resembles as a whole tliat of other albuminoids, 

 and hence consists of trom fifty to fifty-five per cent, of carbon, jjrob- 

 ably six to eight of hydrogen, fifteen to seventeen of nitrogen, twenty 

 to twenty-two of oxygen, and one to two of sulphur. Protoplasm pos- 

 sesses the quality of absorbing water in various quantities, which 

 renders it sometimes extremely soft and nearly liquid, and sometimes 

 hard and firm like leather; but it is usually of a medium degree of 

 density. Its more prominent physical qualities are excitability and 

 contractility, which Kiihne and others have made a special subject of 

 investigation. 



On examining with t'lie microscope the numerous substances con- 

 stituting the various organs of the higher animals, it appears that they 

 all consist of a large number of minute elements, known since Schlei- 

 den and Schwann (1838) by the name of cells ; and in these cells pro- 



