on Green Leaves and other Parts of Plants. 175 
of aniline on leaves and other parts of plants can by any 
means be promoted, it is on the other hand very easy to 
prevent it taking, place entirely. We have repeated the ex- 
periments with various gases and have come to the conclusion 
that, after remaining for some time in an atmosphere of car- 
bonic acid or hydrogen gas, leaves no longer acquire a brown 
coloration when treated with aniline, the former gas being 
perhaps more efficient in this respect than the latter. After 
treatment with boiling alcohol, leaves no longer acquire a brown 
colour on treatment with aniline, nor does the extract yield 
any anilophyll after the addition of aniline and evaporation. 
In the ‘ Chemistry of Chlorophyll ’ it is stated that by the 
action of boiling water leaves do not entirely lose their power 
of reacting on aniline, but on carefully repeating the experi- 
ment we found that after boiling with water continuously for 
a half to one hour the property was completely lost. In some 
cases, however, the power to react on aniline, though lost so 
far as the leaves themselves were concerned, was found to be 
present, though much weakened, in the watery extract. This 
was seen most conspicuously in the case of the leaves of the 
common ash ( Fraxinus excelsior). An aqueous extract of 
ash-leaves was made by boiling the leaves for three-quarters 
of an hour ; a little aniline was added, and the extract kept 
at a temperature of 86° C. After the lapse of about two hours 
crystals of anilophyll were deposited, but the reaction, it is 
true, was considerably slower and the yield less than if the 
leaves had been treated in the usual manner. An aqueous and 
acidulated solution of aniline forms under the same circum- 
stances little or no anilophyll, so that the production of the latter 
must be due to the presence of some transforming agent in the 
extract itself. That the transforming agent is reproduced after 
the quantity originally present is spent, is evident from the fact 
that after filtering off the first deposit, a fresh one is quickly 
produced, and this may be repeated many times. Aqueous 
extracts of other leaves such as mint, holly, &c., react much 
more slowly, showing signs of a crystalline deposit only after 
a day or more, andffhe final yield is generally small. Dis- 
