538 
Richards . — The Respiration of 
young growing tissues as found in seedlings ( Vicia Faba , 
Cucurbita Pepo ) ; and lastly, as with Salix twigs, tissue of an 
entirely different kind. The large majority of the experi- 
ments, however, were performed with potatoes, which lend 
themselves more readily to manipulation, and which react, as 
far as respiration goes, more markedly to injury than any 
of the other tissues tried. 
The injury to which the plants were subjected consisted of 
cutting in various ways. Potatoes and carrots were usually 
cut into four with a sharp knife ; leaves were slit longitudin- 
ally ; while with seedlings the hypocotyl was split, or the tip 
of the root cut off. Immediately after injury, the tissues were 
always washed and only somewhat dried, both to rid them so far 
as possible from the cells killed in the process of cutting, and 
to ensure entire turgidity of the neighbouring parts. As Stich 1 
has pointed out, the amount of C0 2 contained in the small 
quantity of liquid exuded from the cut surfaces is even in the 
case of potatoes practically imperceptible. In those experi- 
ments where it was desired to protect the wounded parts, 
Stich’s method of sealing the pieces together with neutral 
gelatin was necessarily avoided, as the gelatin affords too 
good a basis for the growth of Bacteria when experiments 
lasting several days are to be undertaken. For this purpose 
clay was substituted. The clay employed was tested and 
found to be quite neutral. It was applied to the cut surfaces, 
which were then stuck together in their original position so 
that the oxygen of the air had no opportunity to act on them. 
After one day it was possible to remove the clay in large 
pieces without injury to the tissue beneath, after which the 
wound was washed in a stream of water, which, as shown 
below, does not cause any new increase in the amount of C0 2 
produced. 
L 
II. 
Potato three days after injury 
Same after washing and drying . 
mg. C0 2 per 
hour. 
6.30 
6.15 
mg. C0 2 per 
hour. 
7*45 
7*5° 
1 1 . c., p. 15 . 
