DEATH. 



15 



far above the boiling-point of water (from 20° up to 300'' F.) 

 This subject, however, will be treated of at greater length 

 in speaking of the alleged development of living beings de 

 novo (Spontaneous Generation). 



f. Water. — Lastly, it may be remarked that no vital pro- 

 cesses can be carried on except in the presence of water. 

 This, however, truly depends upon the fact that water is an 

 essential constituent of protoplasmic or albuminous matter 

 in its living state. The necessity, therefore, for a "physical 

 basis " of life, carries with it the necessary presence of water. 

 Life, however, may remain in a 

 dormant condition during long ^.^j 



periods, even in the total ab- 

 sence of water. 



DEATH. 



The non-fulfilment of any of 

 the above-named conditions for 

 any length of time, as a rule, 

 causes death-, or the cessation of 

 vitality ; but, as just remarked, 

 life may sometimes remain in a 

 dormant or "potential" condi- 

 tion for an apparently indefinite 

 length of time. An excellent 

 illustration of this is afforded by 

 the eggs of some animals, and 

 the seeds of many plants ; but 

 a more striking example is to 

 be found in the Rotifera or 

 " Wheel-animalcules " (fig. 2). 



The Rotifers are minute, 

 mostly microscopic creatures, 

 which inhabit almost all our 

 ponds and streams. Diminu- 

 tive as they are, they are nevertheless, comparAtively speak- 



Fig. 2. — Rotifera. Epsf>hom nun /a, 

 one of the Wheel animalcules. Kii- 

 larged about 250 diameters. (After 

 Gosse.) 



