THE CHARACTERISTICS OF ORGANISMS 13 



mulating it beyond its immediate needs, suggests another triad 

 of qualities — growing, reproducing, and developing, which may be 

 profitably considered together. As Prof. Joly says in the essay 

 already referred to: "The organism is a configuration of matter 

 which absorbs energy acceleratively, without limit, when uncon- 

 strained ..." The young leaf spread out in the sunlight utilises 

 a fraction of the solar energy that pours upon it, and does so 

 acceleratively; the more it gets, the more it grows, and the more 

 it can take. This is the unifying idea behind the familiar, though 

 still mysterious, powers of growing, multiplying, developing, and 

 growing again. 



Growth. — ^The power of growth must be taken as a fundamental 

 characteristic of organisms, for it cannot as yet be re-described in 

 chemical and physical terms. The word is a convenient label for a 

 variety of processes which lead to an increase in the amount of 

 living matter, and while there are chemical and physical factors 

 involved in these processes, we are bound in the present state of 

 science to admit that growth depends on the veiled tactics of life. 

 Its results are extraordinary achievements, which would be astound- 

 ing if they were not so familiar. From a microscopic egg-cell there 

 develops an embryo-plant which may grow, say, into a Califomian 

 "Big Tree" — perhaps three hundred feet in height and over three 

 thousand years old. A frog is about three or four inches in length, 

 its egg-cell is under a tenth of an inch in diameter; "the mass of 

 the human adult is fifteen billion times that of the human ovum." 

 In the strict sense growth means an increase in the amount of the 

 organism's living matter or protoplasm, but it is often associated, 

 as in a cucumber, with great accumulation of water; or, as in the 

 case of bone, with the formation of much in the way of non-living 

 walls around the living cells. Growth is usually effected by the 

 multiplication of cells, but in some cases, especially in certain 

 plants, there is first an increase in the mass of living matter, and 

 secondarily a segregation of portions of this into distinct cells — a 

 partitioning that makes it easier for the intricate bustle of life to 

 continue without disorder. When a nerve-fibre grows on and on, 

 feeling its way, as it were, into the distant parts of the growing 

 body, there is growth without cell-division; and the same is some- 

 times seen, even in an adult, when a muscle-cell grows greatly in 

 length and breadth. 



The indispensable condition of growth is that income be greater 

 than expenditure. A variable amount of the food-income is used 

 to meet the everyday expenses of living; the surplus is available 

 for growth; and this must be understood as including, besides 

 increase in size, that imperceptible growth which brings about the 

 replacement of worn-out cells by fresh ones. Green plants are great 

 growers when compared with animals — the Giant Bamboo may 



