The Characteristics of Living Creatures 707 



represented by 40,000,000 pairs at the end of the year, and by 12,- 

 000,000 more pairs the following month! There is a grimness 

 in the well-known remarks of Linnaeus that three flies will con- 

 sume the carcase of a horse as quickly as a lion can. Professor 

 Woodruff observed the common asexual generations of the com- 

 mon slipper-animalcule (Paramecium) for five years between 

 1907 and 1912 and found that there were 3,029 of them, over 

 three every forty-eight hours. Careful calculation showed that 

 they had given evidence of the capacity of producing in the five 

 years a volume of protoplasm approximately equal to 10,000 

 times the volume of the earth. This power of self-increase must 

 be taken account of in our conception of living organisms, and 

 the resulting abundance of life must form part of our impres- 

 sionist picture of Animate Nature. At the autumnal climax of 

 productivity in lakes, there may be to the square yard 7,000 

 millions of a well-known Diatom, Melosira varians, so that the 

 water is like a living soup. 



We have to remember, moreover, the obvious but notable 

 fact that we are dealing not with items like grains of sand, but 

 with individuals, each itself and no other. Mendel put an end 

 to the phrase "as like as two peas." 



Individuals differ greatly in degree of complexity and of 

 integration. Many an Infusorian has an intricate organisation 

 and lives a by no means monotonous life, though it is only what 

 we somewhat fallaciously call "a single cell." Hardly any 

 larger than some Infusorians are some of the Rotifers, sometimes 

 with about 1,000 cells; a minnow has its millions, and a bird its 

 millions of millions. What a contrast between the very incipient 

 integration of a sponge, the intricate division of labour in a 

 "Portuguese Man of War" hesitating between colony and individ- 

 ual, and the compact co-ordination of the circumspect wren. As 

 a recent student of the subject, Mr. Julian S. Huxley, puts it, 

 we are confronted in Nature with closed independent systems 

 with harmonious parts and with capacity for continuance. Such 



