RHYTHMIC NATURE OF ANIMALS AND PLANTS—BROWN 401 
BAR. PRESS. 
POTATO 
METABOLIC RATE 
SALAMANDER 
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{e) 
BAR PRESS. 
METABOLIC RATE 
Ficure 5.—A, The general form of the daily barometric pressure cycle during a summer 
month (upper curve), and the mean daily cycle of potato O; consumption (lower curve). 
B, A comparison of the day-to-day changes in metabolism of both potatoes and sala- 
manders with the concurrent barometric pressure changes. 
large changes due to still unknown forces, which are associated with 
weather changes. The important fact for us here is that the potato 
is informed of how fast the pressure is rising in the morning and 
falling in the afternoon. This we know, first, because how high, or 
how low, the potato metabolism is at 6 in the morning (points A or B 
fig. 5A) of any given day is simply related to how fast the barometric 
pressure was changing from 2 to 6 the preceding morning. And, 
secondly, how high the rate of metabolism in the potato is at 6 in the 
evening of any given day is related to how fast the barometric pres- 
sure was changing from 2 to 6 the preceding afternoon. 
Hence the potato in the form of its daily metabolic fluctuation, 
even in constant conditions of pressure, through being hermetically 
sealed in rigid containers, is in effect informing us through indicating 
in its metabolic changes what the weather distortions were in the 
regular pressure cycle of yesterday. And whatever the means by 
which this information reaches the potato, the same information is pro- 
viding the potato, figuratively speaking, with information as to what 
the weather-associated barometric pressure will be the day after to- 
morrow, by the height of the afternoon peak of metabolic rate. This 
is tending to trace out the form of the barometric pressure changes but 
doing so two days in advance. This is illustrated by the month-long 
study of potatoes and salamanders shown in figure 5B. Notice how 
both kinds of living things generally vary inversely with the baro- 
metric pressure change (bottom curve), but both tend to anticipate 
the pressure changes by an average of 2 days. In fact, every living 
