8 Protoplasm : 



use or absolutely injurious to the plant, as acids, gums and 

 alkaloids, are excreted in various ways, or, like raphides, are shut 

 up in special cells. To make up this loss of substance, the plant 

 is continually engaged in absorbing Carbon dioxide from the air, 

 and various necessary sulphates, phosphates, and chlorides of the 

 metals from the soil. 



Intus-susception. 



Professor Huxley says of this constant absorption of new 

 matter and throwing off of the old : "The addition of molecules 

 "to those which already existed takes place not at the surface of 

 "the living mass but by intus-susception between the existing 

 "molecules of the latter. If the process of disintegration and of 

 "reconstruction which characterize life balance one another, the 

 "size of the mass of living matter remains stationary, while if the 

 "reconstructive process of molecular intus-susception is the more 

 "rapid, the living body grows. But the increase of size which 

 "constitutes growth is the result of a process of molecular intus- 

 "susception, and therefore differs altogether from the process of 

 "growth by accretion which may be observed in crystals, and is 

 "effected purely by the internal addition of new matter so that 

 "in the well known aphorism of Linnaeus the word grow applied 

 "to stones signifies a totally different process from what is called 

 "growth in plants and animals." 



In contradiction to this Professor Schafer says : "Should it be 

 "contended that growth constitutes a test by which we may differ- 

 "entiate between life and non-life, between the animate and inani- 

 "mate creation, it must be replied that no contention can be more 

 "fallacious. Inorganic crystals grow and multiply and reproduce 

 "their like, given a supply of the requisite pabulum." 



The passage I have quoted from Huxley was written in 1875, 

 and of course it might be supposed that between that date and 

 1912 discoveries had been made in the mode of growth of crystals. 

 If so, they must have been made very recently, for in the fifth 

 edition of Dr. Walker's Treatise on Physical Chemistry, published 

 as late as 1910, though he discusses crystals in several places, he 

 nowhere asserts that "crystals grow by intus-susception." True 

 he says : "It was for long supposed that no regular arrangement 

 "of particles could subsist in liquids, the particles of which have a 



