S30 Mr Murray on the Physiology of the Root hi Plmits. 
of this plant, when I received it, were ragged at the tips, and 
ringent or gaping, and they were also quite transparent. Water 
had filled these tubes, and gave rise to a beautiful phenomenon ; 
for the descent of the air-bells was thus exhibited, and closed 
the evidence, if farther proof had been necessary. 
This fact will certainly tend to explain some apparent ano- 
malies. In experiments rnade on plants, in relation to their ame- 
lioration of the atmosphere, contaminated by respiration, where- 
in no beneficial change (or ,a bad one) was exhibited, it must 
be evident, that as carbonic acid gas is excreted by the roots, 
the confined atruosphere might be deteriorated by the gas, when 
the soil is saturated, arising from the earth in which the vege- 
table grows. Besides, these experiments may change our views, 
in relation to the phsenomena of agriculture, while it will satis- 
factorily explain the prompt transit of caustic earths into carbo- 
nates; and thus may be a hint valuable even to the geologist. 
Cress, mustard, the pea, kc. in my experiments, did not even 
swell in ether, sulphur et of carbon, or alcoholic solution of iodine. 
Water perhaps serves chiefly to soften the membrane of the seed, 
or to dissolve any gummy or rather albuminous matter, which 
may seal up the orifices of the excretory, or other vessels. I 
find that when the^^^?, bean, &c. remain some time in distilled 
water, and such swell, the fluid becomes opahe. It is blackened_ 
by sulphuric acid, and white fakes or threads appear on being 
heated with alcohol., muriatic acid, he. or with a temperature 
amounting to 176° Fahrenheit, and that it has all the characters 
albumen. 
Carbonic acid distils copiously from the hilum or scar, parti- 
cularly noticeable in the pea or bean ; and here the air-bells will 
appear ranged in parallel rows. I threw a bean, when the testa 
or skin was rent, and the corculum advancing into the attitude 
of the plumula, into distilled water, heated to 100° Fahrenheit. 
The carbonic acid gas spun out in a continued streamlet for 
sometime, and it issued from the end of the hilum adjoining 
the corculuiq. The hilum is almost always studded over with 
air-bells of carbonic acid gas. 
In the course of my researches, I have met with nothing to 
disturb the opinion I have uniformly maintained, on the beau- 
vtiful arid beneficent reciprocity vvhich exists between the animal 
