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214 CORRESPONDENCE.
timation of tlie existence of a Cocoa-nut-tree growing at Cawarral was given by
Mr. Robert Spencer. I shortly aftej" secured specimens of the leaves, flowers,
and fruits for identification, which I forwarded in November, 1864, to our
illustrious Australian botanist. Dr. Ferdinand von Mueller, who mentioned
the discovery in his ' Fragmenta Phytographiae,' vol. v. p. 49, and idtimately
in his review of the Australian vegetation for the Melbourne and Paris Ex-
hibitions. The aboriginals unroot the already growing plant, to secure the
smallest part of the albumen remaining eatable. Does not such want of fore-
thought by these children of nature establish sufBciently one of the principal
causes of the paucity of the Cocoa-nut on our eastern Australian coast ? I
have no doubt tliat, as the settlers on the coast will increase, they will reveal,
as has been already the case in a few instances, the occurrence in several otlier
localities of that useful Palm, and still extend its geographical distribution,
wliicli seems now to be limited to so few individuals. Will it ever be found in
large groups ? I am, etc.,
A. TnozET.
RemarJcs on Dr. Lindsay s Paper " On Chemical Reaction as a Specific
Character in Lichens."
Dr. Lindsay, in his paper (Journ. Linn. Soc, Botany, pp. 36-63, 1869),
attempts to show the slight degree of faith that ought to be placed in the che-
mical criteria proposed by me for distinguishing witli facility one from another
a great number of species of Lichens, between which, in the absence of these
means, it is frequently extremely difficult, or even impossible, to discriminate.
It is not my intention to follow the author througli tlie long development he
has thought proper to enter into ; such a task would assuredly be altogether
superfluous, for evidence is not to be denied, and to any one able to see, and in
suitable conditions for such researches, the reactions here in question are as
evident as they are easy to produce. Nothing in them is " supposed," as Dr.
Lindsay would have it.
The reddish hue sometimes produced on the altered basis of certain old
thalli of, e. g., Platysma nivale by the application of potash or of liquid ammonia,
has nothing to do with the chrysophanic acid reaction, as contended by
Dr. Lindsay ; it is but the result of an accidental or anomalous state of tliese
Liclieus. All the other examples set forth by him are like tlie one just alluded
to, or altogether inaccurate. \ In like manner, if the thallus of Phyneia parietina
or of Plaeadiiim mnrorum, growing in the shade, becomes greenish, and is
shown to contain less chrysophanic acid, is the chemical character belonging
to these Lichens in their normal or typical state impaired on that account ?
Dr. Lindsay speaks of the numerous cases he has observed of inconstancy in
chemical character ;
but is he quite sure the Lichens he has liad to deal with are
correctly named ? Is it not probable, rather, that where lie fancied he dis-
covered variability in the reactions (the result, according to him, being some-
times positive and sometimes negative) he had to do with different species ?
He himself allows lie is unacquainted with the common Parmelia oUvetorumf
Ah una disce omnes.