GENERAL PROPERTIES OF LIVING MATTER. 17 



same, and the main form of propagation is always a division. 

 Even in the most highly developed mammals the embryo originally 

 forms a part of the mother-body, and, after having grown, by 

 internal gemmation or endogenous production, up to a certain 

 size, separates from the vehicle, the womb, and represents a new 

 individual. (See Fig. 1.) 



Remak was the first to draw attention to the three forms of 

 propagation, but he was not aware of their being materially 

 identical, though morphologically different, manifestations of one 

 and the same process. 



There is a striking peculiarity about generation, viz. : the 

 resemblance of the newly formed body to the producing organ- 

 isms, the parents. It is an easy matter to understand that both 

 individuals will be alike in a case of simple division, because both 

 formerly made one single body ; but how shall we explain the 

 remarkable fact that, in higher animals, the offspring so closely 

 resembles the progenitors, though only very minute parts of 

 these the ovum and the spermatozoids contributed to give 

 rise to a new individual ? 



The opinion of E. Hering, that organized matter is endowed 

 universally with an "unconscious memory," a function upon which 

 depends, besides the capacity of imagination, of thinking, 'of 

 habit, also nutrition and propagation, is not an available one. I 

 therefore take into consideration only the three modern hy- 

 potheses of Charles Darwin, Louis Elsberg, and Ernst Haeckel. 

 Darwin promulgated in 1868 the " Provisional Hypothesis of 

 Pangeiiesis," which consists essentially in the assumption that 

 through all stages of development the living cells or units of the 

 body throw off small granules, or " gemmules," which accumulate 

 to form the sexual elements ; and all the cells of the body, there- 

 fore, participate indirectly in the new formation of organisms. In 

 1872, Elsberg published his theory of the " Regeneration or Pres- 

 ervation of the Plastidules." He lays down the proposition that 

 the germ of every living individual contains plastidules of all its 

 ancestors ; so that these are bodily regenerated in their offspring, 

 simply because bodily particles are preserved directly from gener- 

 ation to generation. In 1875, Haeckel announced the hypothesis 

 of the " Perigenesis of the Plastidules," according to which, in 

 opposition to the opinions of Darwin and Elsberg, no regeneration 

 or preservation and transmission of plastidules takes place, but 

 only a transmission of motion through inheritance. 



Among these theories, I confess that that of Elsberg seems 

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