57 8 THE POPULAR SCIENCE MONTHLY. 



nized by Harvey, and first expressed in his famous aphorism, " Omne 

 vivum ex ovo" an egg, whenever it occurs, consisting essentially of 

 a minute globule of protoplasm. 



What is the origin of this universal, white-of-egg-like material? 

 As little is known of the history of the first production of protoplasm 

 as of that of the elements hydrogen, oxygen, nitrogen, carbon, etc., 

 of which it is composed. So far as yet discovered, all protoplasm, 

 whether vegetable or animal, is derived from pre-existing protoplasm. 

 The spontaneous production of living matter from non-living mate- 

 rials has never been satisfactorily proved. The particular kind of pro- 

 toplasm which we are about to consider viz., the human germ is the 

 combined derivative of certain glands which exist in separate adult 

 human beings who represent the opposite sexual polarities belonging 

 to all except the lowest vegetable and animal types. At the earliest 

 recognizable stage of his existence man may therefore be regarded, 

 physiologically, as a secretion. Zoologically, to what rank is he, then, 

 entitled ? The undeveloped human ovum, immediately after its fer- 

 tilization, corresponds in structure to the lowest known order of the 

 most simple class of animals, the Protozoa, which stand at the very 

 foot of the zoological scale. To this most humble of all known living 

 creatures Professor Haeckel has given the name of Moner, a word of 

 the same origin as monad, and expressive of ultimate simplicity and 

 primitiveness. 



More simple even than the moner, however, is the bathybius, found 

 on the deep-sea bottom, and described by Professor Huxley as consist- 

 ing of an ill-defined mass of a slime-like material possessing all the 

 properties of living protoplasm. Even granting with skeptics on this 

 point that the existence of bathybius is not satisfactorily proved, we 

 may nevertheless assert with confidence that, as the natural predecessor 

 of the moner, it ought to exist, and will some time be discovered, just 

 as certain unobserved heavenly bodies have been partially described 

 and located by astronomers long before the telescope had penetrated 

 the obscurity in which they were hidden. 



Through the processes of nutrition, under the combined influences 

 of growth and development, this non-nucleated mass of living proto- 

 plasm (the human ovum) acquires a nucleus ; in other words, there 

 appears at its center a minute speck of matter slightly more opaque 

 than the surrounding matter. Differentiation has therefore begun ; 

 that is, a difference of parts has made its appearance. How does this 

 nucleus (to which, in cell-physiology, so much importance is attached) 

 differ from the surrounding: matter which constitutes the bulk of the 

 germ-? Chemically, it is more active; it is believed to be the part 

 where nutrition (the assimilation of new material) mainly takes place. 

 Its greater chemical, and, therefore, nutritive activity, is shown by its 

 deeper staining with coloring -matters, such as carmine and hoema- 

 toxylin, and by the fact that, with the access of nutriment, fresh nu- 



