GROWTH OF THE LIVING THING. 61 



crystal, or is it formed from within ? Which is the 

 oldest part of the capsule, its external or internal 

 surface r If the new matter were deposited upon the 

 outside, we should expect to find that the membrane 

 would become thicker and thicker as the growth of the 

 organism advanced, while the central portion would 

 remain unaltered. This, however, is not the case. 

 On the contrary, we find that as growth proceeds, the 

 wall in most cases becomes considerably thinned. It 

 is clear, therefore, that any increase in size cannot 

 be due to deposition from without. The matter de- 

 posited upon the inner surface of the capsule is 

 always softer than its general substance, and the 

 external surface of old capsules is cracked and ragged. 

 This ragged portion is oldest. In many of the algas 

 (sea-weeds) this external stu-face serves as a nidus for 

 the development and growth of smaller algse — a fact 

 which clearly shows it has ceased to be active, is 

 undergoing disintegTation, and becoming fitted for 

 the pabulum of other things, and no longer capable 

 of resisting the action of external conditions. This, 

 the oldest part of the capsule, is now undergoing 

 decay, and the small algse are li\Ting in part upon the 

 products thus produced. The new material is in- 

 variably added upon the inner surface of the capsule, 

 layer within layer. Of the several layerSuihe innermost 

 is the youngest, and the outermost the oldest portion 

 of the structure. From this it follows that the in- 

 animate material for the nourishment of these living- 

 things must pass through the outer membrane, and be 

 taken up by the living matter within, which commu- 

 nicates to it the same properties and powers which 

 this living matter itself possesses, and which it has 

 inherited from pre-existing particles. At present we 

 cannot get further than this. I am ignorant of the 

 cause of the changes which occur, but the facts as I 

 have stated them are true. 



91. luiyortance of tliese changes in bioplasm. — 



