SCIENTIFIC SUMMARY. 
2l£ 
is simultaneously affected, causing one or more contacts to be liberated, and 
as many additional resistance-coils to be thrown into circuit ; the result being- 
that the temperature of the strip varies only between very narrow limits, and 
that the current itself is rendered very uniform, notwithstanding considerable- 
variation in its force, or in the resistance of the lamp, or other extraneous 
resistance which it is intended to regulate.” 
PHYSIOLOGY. 
The Venom of Serpents. — The poison of serpents has generally been 
regarded as a sort of poisonous saliva, acting after the fashion of soluble 
ferments. M. Lacerda, of Rio de Janeiro, has made some observations upon 
the venom of a rattlesnake, which lead him to believe that this fluid con- 
tains formed ferments analogous to the Bacteria. ( Comptes rendus, Decem- 
ber 30, 1873.) Placing a drop of the poison upon a glass slide previously 
washed with alcohol, and slightly warmed, he examined it under the micro- 
scope, and saw “ a sort of protoplasmic filamentous matter, formed by a cel- 
lular aggregation, arranged in an arborescent form, like that of certain 
Lycopodiacese.” He observed the formation of spores within a thickened 
filament, which finally broke up and disappeared, setting free the spores, 
which then affected a linear arrangement. He describes the modes of 
multiplication of these spores, namely, by scission and by interior nuclei. 
The phenomena observed in the blood of animals killed by the bite of the 
snake were as follows : — The red globules presented small bright points on the 
surface of the disc ; these sometimes formed projections, and became more 
and more numerous. Finally, the globule was completely destroyed, and 
replaced by a number of very brilliant ovoid corpuscles, endowed with- 
spontaneous oscillatory movements ; these ovoid corpuscles did not separate 
from the mass of the globules, but remained within it, and the globules 
became fused together to form a very different amorphous paste. Alcohol 
swallowed, or injected beneath the skin, was found to be the best antidote. 
Function of the Chlorophyll in Green Planar ice . — M. P. Geddes has ex- 
perimented on a green Plana?'ia, which is very abundant at Roscoff, with 
the view of ascertaining what is the function of the chlorophyll, which 
has long been known to exist in such worms. The Plcmarice were fond of 
exposing themselves to the light on the bare sand in shallow water, and 
when placed in a small aquarium they went always towards the side from 
which the light came. When exposed to the sun their movements were- 
considerably accelerated, and in a few minutes small bubbles of gas appeared 
here and there, and increased in number and in volume, just in the same way 
as with a green seaweed under similar circumstances. The gas evolved wae 
easily collected, and in the course of the day enough was obtained to fill a 
small test-tube, and it appeared to be dilute oxygen by its effect upon a 
nearly extinguished match. By further experiments with potash, it was 
found to contain very little carbonic acid ; and the addition of pyrogallic 
acid showed the presence of oxygen by the dark brown coloration produced 
and the ascent of the liquid in the tube. M. Geddes found that the gas- 
produced by these Planarice contained 45-55 per cent, of oxygen. The 
