1 
Hourly 
growth. 
Tenipera- 
ture. 
8—9 
a. m. 
1.40 
21.0 0 C. 
10 
•V 
1.70 
21.5* 
11 
» 
2.20 
21.7 
12 
— 
2.70 
22.8 * 
\ 
p. m. 
3.10 
23.5 
2 
„ 
3.30 
23.0 
3 
M 
3.00 
22.6** 
4 
i! 
3.30 
22.5 
* yellow liglit. 
** daylight. 
Here the average acceleration is nearlv 0.?7. 
.. 1.70 — 1.40 — 0.27 
.. 2.20 — 1.70 — 0.27 
.. 2.70 — 2.20 — 0.27 
.. 3.10 — 2.70 — 0.27 
.. 3.30 — 3.10 — 0.27 
. . 3.00 — 3.30 — 0.27 
. . 3.30 — 3.00 — 0.27 
0.03 -f- 
°- 23 4- (yellow light) 
0.23 + 
0.13 -f- yellow light) 
0.07 — 
0.37 — (daylight) 
0.03 +. 
A comparison of these resulls shews at once that the more hiehlv 
refrangible rays of the speclrum are those which are especially aclive in 
retarding growth, whereas the rays of low refrangibility have no more 
eflect upon il than darkness. This agrees with what is already known 
with reference to the influcnce exercised by the two halves of the spectrum 
upon the growth of organs of complicated slructure. 
These observations prove that the growth of so simple a slructure 
as the hypha of a Fungus is afTected by the action of light in the saine 
way as that of a complex organ, with the single difference, that the for¬ 
men is able to react more rapidly than the latter. 
It now remains to seek some explanation of the phenomena. Il is 
not probable that the retarding action of light is an indirect one, that it 
airects the activity of the growing cells only in so far as it modifies the 
chem.cal processes of tbeir nulrition. Whatever direct evidence can be 
oblained lends to prove that the Chemical processes are more activelv 
carried on in the presence than in the absence of light. The decorapo- 
sition of carbonic acid and the formation of starch in the chlorophvll- 
grains with evolution of oxygen, lakes place only linder the influcnce of 
light. Pfeffer i) has shewn, that the conversion of asparagin into proteid 
4) Jahib. f. wiss. Bot. Bd. VIII. 
