Notes . 
275 
metre of Tropaeolum- leaves, under favourable conditions, we found 
it amounted to 7-2 grams per square metre in 8 hours, or about 
0-9 gram per square metre per hour; so that we see the actual 
amount of starch present in the leaf at any one time represents only 
a small proportion of the 10 or 12 grams of material assimilated 
during a summers day of sunshine. 
This conclusion is even more strikingly shown in our experiments 
with the leaves of the Sun-flower, in which we determined the total 
amount of material assimilated in 12 hours of insolation, and also 
the actual increase in the amount of starch during the same period. 
Grams per sq. metre. 
Starch at 5 a.m. 1-05 
Starch at 5 p.m. 2-45 
Increase in starch in 12 hours 1-40 
Total products assimilated in 12 hours 12-0 grams. 
During the time that one square metre of the leaf has assimilated 
12 grams of material from the atmosphere, the starch has only 
increased by 1-4 grams. If, therefore, Sachs’ idea is correct that 
all the assimilated products pass through the form of starch, the 
deposition and dissolution of that substance in the leaf-cells must 
take place at a most astonishing rate. We have however failed 
to find any proof of starch being a necessary link between the 
sugars of assimilation and the sugars of translocation ; the pro- 
babilities all point to the starch being elaborated in the assimilating 
cells only when the supply of nutriment is in excess of local require- 
ments, most of the assimilated products never passing through the 
stage of starch at all. Later on we shall have to say something 
about the nature of the substance from which the starch is elaborated 
by the chloroplasts. 
We must now turn to the occurrence of diastase in the leaf, 
and consider the part it plays in the dissolution of the starch formed 
by the chloroplasts. A careful examination of this question was 
rendered all the more necessary since it has been strongly denied 
recently by Wortmann 1 that diastase plays any part in the dissolution 
and translocation of starch in leaves. 
To prove his case Wortmann relies upon the following facts; which 
he believes he has established. 
1 Bot. Zeitung, 1890, p. 582. 
