PROTOPLASM. 367 



to some degree irritable, all are capable of reproduction of their own 

 kind of cells, and so on. 



Thus, from the beginning of his career, as a microscopic speck of 

 living matter, to its close, although he figures as the most highly en- 

 dowed and transcendent of beings, man, biologically considered, is 

 protoplasm, protoplasm, only protoplasm ; and, whatever his perfec- 

 tions, regarded as a member of the animal series, he has the high 

 privilege of knowing if not of feeling himself the brother of all living 

 things. With Job, he may say unto the worm, " Thou art my mother 

 and my sister." " Oh, why should the spirit of mortal be proud?" 



" What, then, is protoplasm ? " we are inclined to ask, almost at 

 the close of our attempt at a description. 



Professor Huxley has called it "the physical basis of life" an 

 expression which has become classic in the scientific world while life, 

 in its turn, is defined as a property, or congeries of properties, of 

 protoplasm. Pflttger has naively said, " Albumen lives " that is, 

 becomes protoplasm " when it begins to take in oxygen " ; and Fos- 

 ter, with equal simplicity, remarks, " The whole secret of life may 

 almost be said to be wrapped up in the occult properties of certain 

 nitrogen compounds." 



Lewes, in his own graphic style, has said, "The organism and its 

 environment are the two factors, of which life is the product." 



Protoplasm is the agent by which the energy of non-living matter 

 is converted into that of living matter the sacred fire which is never 

 permitted to go out, but perpetually glows on the altar of Nature, fed 

 by the vestal forces of the environment, and burning ever higher and 

 higher through those twin influences, heredity and the survival of the 

 fittest. 



This true " vital spark " is not only transmitted from generation to 

 generation in the entire animal world, each reproducing its own kind, 

 but it has been handed on, through vast geological ages, from branch 

 to branch of the animal tree, since that far-off period when the " dawn- 

 animal " first left its imprint in the hardening mud of its slimy bed at 

 the bottom of a vast ocean whose waters were still under the influence 

 of the earth's heated interior, when this ocean was overhung by a sky 

 dark with clouds so dense that day and night were scarcely distinguish- 

 able, and shutting in an atmosphere heavy with carbonic-acid gas. 



The relations observed between the fossil animals thus far discov- 

 ered, the existing animal series, and the embryonic forms of all ani- 

 mals at the various stages of development of their respective embryos, 

 are most significant. The earliest, oldest known fossil (the Eozobn 

 Canadense, or " dawn-animal," the genuineness of which, though de- 

 nied by some, is more than probable) belongs to the same class of or- 

 ganisms as the moneron and the amoeba of to-day, which stand at the 

 bottom of the scale of animal life ; and the geological ladder in its 

 ascent bears upon its successive rounds fossils which correspond, with 



