60 DEATH OF THE MILDEW. 



the latter a slow one. In a few hours bioplasm may 

 multiply itself a hundredfold, but days or weeks may 

 be required for the formed material to double in 

 amount. If, after rapid growth from exposure to 

 favourable conditions, the bioplasm be brought under 

 the influence of adverse circumstances, the formed 

 material gradually increases in thickness. At the 

 same time the amount of bioplasm becomes less and 

 less, for it undergoes conversion into the formed ma- 

 terial. The latter, therefore, becomes thickened by 

 deposition, layer within layer. At last a mere speck 

 of bioplasm may remain, surrounded by a very thick 

 investing membrane, which acts as a most efficient 

 protection to the trace of bioplasm that remains. 

 This being protected resists the influence of extreme 

 cold and retains its vitality until external conditions 

 become again favourable, when the trace of living 

 bioplasm soon increases, pushes through spaces or 

 orifices in the thickened membrane, much of which it 

 even consumes as pabulum, and the rapid growth 

 already referred to is resumed. 



95. Death of the mildew. If such a living thing 

 be placed under certain unfavourable conditions, its 

 vital properties will be destroyed. The transparent 

 living matter in its interior will shrivel up and die, 

 but this will be attended by no obvious alteration in 

 the external membrane. The part which exhibits 

 form (formed matter) remains ; that which is without 

 form (living matter) is alone killed or destroyed. 



96. How is the new matter added produced ? In the 

 thickening of the outer formed matter then, how is 

 the new material produced ? Is the thickening oc- 

 casioned by deposit upon the outer surface of the in- 

 vesting membrane, or is the new matter produced by 

 the soft, formless matter in the interior ? To put the 

 question still more simply, is the transparent capsule, 

 the so-called cell-wall, formed by deposition of matter 

 from the fluid surrounding it, as in the increase of a 



