Notes. 
279 
In considering the very variable diastatic function of the leaves of 
plants it is a matter of considerable interest to determine if there is 
any correlation between the amount of diastase in the leaf, and the 
facility with which the particular leaf forms starch in its chloroplasts. 
Unfortunately we do not at present possess a sufficient number of 
accurate observations on the starch-production of various plants to 
determine this point with certainty. We are not however without 
some data to guide us. 
A. Meyer 1 has generalized his observations on the facility of starch- 
production in leaves by arranging the Natural Orders of the Dicoty- 
ledons which he has examined in five different classes, according to 
the amount of starch which they can produce in their leaves under 
favourable conditions. In the first class he places the Solanaceae 
and the Leguminosae as being able to form large quantities of starch. 
As already shown, the Leguminosae are highly diastatic, pre-eminently 
so in fact, and the three Solanaceae examined Nos. 36-38 come next 
to them in this respect. 
Amongst the Monocotyledons it has been long known that certain 
of the Liliaceae form little or no starch in their leaves. The 
Liliaceous plants are certainly, according to our experience, very poor 
starch-formers, and it is interesting to note that they are also very poor 
in diastase, especially those species which never produce any starch at all. 
Of the three Liliaceous plants given in the table, Nos. 23-25, Funckia 
sinensis can produce a moderate amount of starch, whilst Allium Cepa 
and Hemerocallis fulva are not starch-producers. It is a noteworthy 
fact that the first-named plant is more diastatic than the two last. 
Our observations certainly suggest that readiness of starch-production 
in the leaf under the action of light is related to the occurrence 
of diastase, and this fact alone renders it probable that the dissolution 
of the starch is in some way or other brought about by the enzyme. 
That the diastatic function of leaves varies within certain limits in 
the same plant is evident from an inspection of Nos. 12-20 in the 
table, which show the amount of diastase met with in the leaves of 
Tropaeolum taken at different times. 
We have endeavoured to ascertain if these fluctuations in diastase 
are in any way periodic, and if they are governed, like the fluctuations 
of starch in the leaf, by any external conditions to which the plant has 
been subjected. 
1 Bot. Zeitung, 1885, Nos. 27-32. 
