1899] APPLIANCES FOR PHYSIOLOGY 263 
diameter of the burette. The water will rise vigorously. We 
then have side by side two similar burettes, to one of which 
innumerable tiny absorbing hairs are attached, and to the other 
asingle huge one. It is true there is the difference between 
them that the root hairs have a semi-permeable lining of proto- 
plasm absent from the shell, and that they do not open directly 
into tubes as the shell does, but these differences are of minor 
account in comparison with the fact that it is fundamentally the 
same physical force that produces the absorption in the two 
cases, 
5. A respiration apparatus. 
Of prime importance in plant physiology is the exchange of 
gases in the processes of respiration and photosynthesis. It is 
Fic. 5.—Respiration apparatus. 
the more j to 
°re important in elementary courses, since nearly every 
Stel beg ey reciprocal exchange between animals and Sr 
It hel 4 ails even to recognize that respiration bet pene 
gery to clear a student’s mind on this subject I Ao 
defor ue importance of respiration are made plain to 
he has had a chance to confound its processes with those 
: Photosynthesis. seeds offers 4 good 
of 
cha The germination ie 
nce } cies . 
to demonstrate the gas exchange in respiration unl 
