Newman.—Speculations on Physiological Changes. 89 
tons) less than when at home. Though in healthy people it may be difficult to | 
detect many changes arising from these causes, we may see that they really 
are very powerful. Phthisical patients, after a short residence here, improve 
(the pathological changes fade out), and often they become robust. A 
lessened atmospherie pressure is also very beneficial in many acute diseases, 
and especially in those of the lungs. The fierce New Zealand gales pump 
air into rooms at high pressures, and thus increase disease and retard 
recovery. Diminution of atmospherie pressure, too, causes a change in the 
shape and size of the various organs—e.g., the Aymaras, who inhabit the 
Andean heights, have long deep chests, with large lungs and short legs ; 
these and other peculiarities of structure in them are directly dus to lowered 
atmospherie pressure. 
People who climb lofty mountains soon experience great fatigue because 
their legs feel so heavy. When walking, our limbs swing freely like 
pendulums, and feel of little or no weight because of the peculiar formation 
of the hip, knee, and ankle-joints. If all the muscles and ligaments were 
cut through which attach the thigh to the trunk it would not fall off, because 
the atmosphere presses the head of the femur against the acetabulum. This 
pressure is 25 pounds. In like manner the leg is attached to the thigh by a 
large joint, the pressure on which is 60 pounds; so with the ankle-joint 
—thus the weight of each limb, both upper and lower, is much lessened, 
As in ascending a height, so in any case where the pressure is lessened, the 
weight of the limbs will increase, and therefore fatigue would a little earlier 
set in during a long walk in New Zealand than in England. 
Yet other altered climatic conditions affect the immigrant. Though the 
amount of heat received by each hemisphere is exactly equal, yet is its 
distribution unequal; for, owing to the earth’s position, the southern 
summer is nearly eight days shorter than the northern, and its winter so 
much longer (Somerville). The solar rays fall more directly on the southern 
hemisphere, and their heating power is consequently greater by one- 
eighteenth of their whole intensity ; but as solar rays are composed of heat, 
light, and actinic rays, all three act more directly and more intensely in the 
southern hemisphere. As each of these varieties powerfully affects all 
organic and inorganic substances, therefore variations in the amount or 
intensity, or distribution of all combined, or of each one singly, affects the 
immigrant both directly and indirectly. In vegetation is easily seen the 
effect of sunlight—for vegetation grown in the dark is pale, and often sickly. 
Moreover, Sachs, a German botanist, has shown that, m the sunlight, starch 
grains travel in ten or fifteen minutes from the stems of plants to the 
chlorophyll grains in the leaves, and that these and many other changes 
"would not occur if the light and actinic rays were absent. He also shows 
