CYTOLOGY. 



total terrestrial mass of matter ever became 

 vitalized; a ten-millionth of it is one well- 

 known estimate. In many ways Life is lim- 

 ited in quantity ; in fact, it often limits itself 

 with a destructive violence. Yet this quan- 

 tity has remained about the same through the 

 later geologic ages, it is supposed; still one 

 is inclined to think that, as the Earth kept 

 cooling off in the earliest stages, the life-area 

 of it, starting from the polar point, must have 

 enlarged, and therewith in proportion the 

 primal life-stuff must have increased. 



So in one form or other we have to con- 

 ceive a primal original reservoir of life-stuff, 

 be its locality arctic or equatorial, in the Sar- 

 gasso Sea or in the Nile-bed, or indeed ev- 

 erywhere. Moreover we hardly dare limit 

 this elemental protoplasmic material to early 

 time; it still must exist in some way and be 

 at work, if it could only be found; that first 

 creative living individuation of Nature has 

 never stopped, can never stop but with Life 

 itself. 



Given, then, our planetary evolution from 

 the Heliosphere, Earth-life must have arisen 

 in time and place along with the right tem- 

 perature and other accordant conditions, and 

 attained a certain amount of vital material 

 whose quality has been improving ever since 

 through evolution without much change in 



