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SRE oa ce ae AR MIE TERN, aR SES gee a Se be oy eR EF 
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1883.] | Organic Physics. 137 
for nutriment has correspondingly increased, while new nutrient 
molecules have been stored up in their vicinity. The tide of life 
turns. From running down it begins to run up. The process of 
assimilation gains the supremacy, and oxidation of the tissues in 
great part ceases. During this period there is a marked change 
in the conditions of life. Assimilation consumes energy. The 
chemical synthesis cannot go on unless energy be supplied. That 
which was yielded during the period of oxidation no longer re- 
mains in the body. It has been used up in various methods. 
Temperature energy remains, but that must be kept up, and can- 
hot be reduced in aid of other purposes. It is evident, then, that 
while assimilation is specially active animal activity must decline 
orcease. Not only is there no store of energy for mental and 
muscular action, but there is none for chemical action. Energy 
must be provided for this purpose, and much of the oxygen 
which now enters the body is necessarily engaged in this new 
duty. Oxidation continues, but it is oxidation of the hydrocar- 
bons of the blood or of other low-atomed molecules, to supply 
the energy required for the rebuilding of the tissues. The sleep- 
ing succeeds the waking state, and animal is replaced by vegeta- 
ble activity. 
It will be perceived, by the terms of this hypothesis, that there 
is required no actual cessation of the two life-processes. Each, 
in fact, has two separate phases. During the waking period oxy- 
gen is busy in the tissues, while nutriment is being actively ab- 
sorbed, prepared and stored up for future use. During the slee T 
ing period nutrition is busy in the tissues, while oxygen is partly 
engaged in reducing the innutritious ingredients of the blood and 
the tissues, and yielding energy for temperature and assimilation, 
and is partly stored up for future use. Thus each process aids 
the other, and each succeeds the other in its work upon the tis- 
Sues. Now oxygen gains the mastery, life thrills in every nerve 
and muscle, the chemical molecules drop to a lower level of in- 
tricacy and the body springs into its active, waking state. Now 
nutrient affinity gains the mastery, vital activity ceases, the body 
is being lifted up hill preparatory to another fall, and the passive, 
sleeping state supervenes. 
Hest at ares life there is only one process, instead of two, as in 
Us. _ Plants always sleep. Oxidation is active, but itis sim- 
char zi pe to the oxidation that takes-place in animals 
