722 THE POPULAR SCIENCE MONTHLY. 



manifestations, there is protoplasm ; wherever there is protoplasm, 

 there, too, is life. Thus, coextensive with the whole of organic nature 

 every vital act being referable to some mode or property of proto- 

 plasm it becomes to the biologist what the ether is to the physicist ; 

 only that instead of being an hypothetical conception, accepted as a 

 reality from its adequacy in the explanation of phenomena, it is a 

 tangible and visible reality, which the chemist may analyze in his 

 laboratory, the biologist scrutinize beneath his microscope and his dis- 

 secting needle. 



The chemical composition of protoplasm is very complex, and has 

 not been exactly determined. It may, however, be stated that pro- 

 toplasm is essentially a combination of albuminoid bodies, and that 

 its principal elements are, therefore, oxygen, carbon, hydrogen, and 

 nitrogen. In its typical state it presents the condition of a semi-fluid 

 substance a tenacious, glairy liquid, with a consistence somewhat like 

 that of the white of an unboiled egg* While we watch it beneath 

 the microscope, movements are set up in it : waves traverse its surface, 

 or it may be seen to flow away in streams, either broad and attaining 

 but a slight distance from the main mass, or else stretching away far 

 from their source, as narrow liquid threads, which may continue sim- 

 ple, or may divide into branches, each following its own independent 

 course ; or the streams may flow one into the other, as streamlets 

 would flow into rivulets and rivulets into rivers, and this not only 

 where gravity would carry them, but in a direction diametrically op- 

 posed to gravitation : now we see it spreading itself out on all sides 

 into a thin liquid stratum, and again drawing itself together within 

 the narrow limits which had at first confined it, and all this without 

 any obvious impulse from without which would send the ripples over 

 its surface or set the streams flowing from its margin. Though it is 

 certain that all these phenomena are in response to some stimulus 

 exerted on it by the outer world, they are such as we never meet with 

 in a simply physical fluid they are spontaneous movements resulting 

 from its proper irritability, from its essential constitution as living 

 matter. 



Examine it closer, bring to bear on it the highest powers of your 

 microscope you will probably find disseminated through it countless 

 multitudes of exceedingly minute granules ; but you may also find it 

 absolutely homogeneous, and, whether containing granules or not, it 

 is certain that you will find nothing to which the term organization 



* In speaking of protoplasm as a liquid, it must be borne in mind that this expression 

 refers only to its physical consistence a condition depending mainly on the amount of 

 water with which it is combined, and subject to considerable variation, from the solid 

 form in which we find it in the dormant embryo of seeds, to the thin, watery state in 

 which it occurs in the leaves of Valisneria. Its distinguishing properties are totally dif- 

 ferent from those of a purely physical liquid, and are subject to an entirely different set 

 of laws. 



