Genesis of Man. 313 



moner up to man, diverse lines of growth begin, branches not 

 followed by the human embryo which keeps on in its direct 

 course, and touching only these other forms at the points of 

 divergence. 



There is a difference between the moner and a cell: the moner 

 is a lower stage of existence than the cell, the latter is distinguished 

 by a certain differentiation which engenders a nucleus within its 

 protoplasm. The moner has no nucleus. 



The multiplication of all forms of life which occupy a place but 

 little above the lowest, is brought about by the union of two 

 cells, designated respectively male and female. The former, or 

 spermatozoon, is a true nucleated cell, an infusorium ; the latter, or 

 ovum, is an amoeba. 



Following up the growth of a human being, the sperm-cell 

 penetrates the ovum, and the two at once coalesce and lose their 

 individuality ; the nuclei of both disappear, and there results a 

 mass of protoplasm. All trace of internal cell-structure having 

 thus disappeared, the result of this union corresponds to the 

 moner. Two perfect cells have thus produced, by their union, a 

 form the very lowest in the scale of being; the cell has gone back- 

 ward in its process of evolution. Every animal begins its life at 

 this point, which is the cytod, or, as Hackel names it, the moner- 

 ula stage. 



The next change observed is the formation of a nucleus, when 

 the monerula becomes a true cell ; but, owing to the qualities 

 conferred upon it by the sperm-cell which it has absorbed, the 

 cell is altered, in its nature and capabilities, from the earlier type 

 in its life-history. This later form represents the amoeboid stage 

 of the human being. 



The next condition begins with the binary subdivision of the 

 nucleus and the surrounding protoplasm, which process is re- 

 peated until the entire contents of the cell are converted into a 

 mass of minute cells. This is the morula stage, a condition also 

 represented by living organisms. 



The morula is now changed by the absorption of fluid from the 

 surrounding medium, and this, collecting in the central portion of 

 the morula, presses the minute cells outward until they form a 

 layer just within the original enveloping membrane. There is thus 

 produced the blastosphaera stage, and the layer of cells mentioned 

 is known as the blastoderm. 



The gastrula follows, and differs from the last form by the 



