land. 1 97 
1899] BRIEFER ARTICLES 69 
reddish-brown particles in the tracheides, vessels, and medullary 
parenchyma. It is presumed that it gained entrance to these tissues 
before the death of the tree and had therefore passed through the con- 
ducting elements and been absorbed by the living cells of the medullary 
rays. This tissue also contained starch both in the 
cells containing copper and those free from it. It is 
not easy to predicate in what form the copper was 
taken up by the plant, but probably as a carbonate, 
which would be reduced to the metallic state in the 
tissues. The large amount of the substance present 
rather supports Lehman’s conclusions that it does not 
exert a marked injurious influence upon plants. Its 
occurrence aa the eae eee fda that aap otk 
of Quercus macro- 
it had been freely absorbed during nearly a decade. carpa, containing 
However, the death of the tree may have been finally particles of metal- 
: ; lic copper 
caused by the influence of this substance. 
Mr. J. B. Skertchly has found that Polycarpea spirostylis F. von 
Mueller occurs in such close connection with the copper deposits of 
North Queensland in such an invariable manner that it may be used as 
indication of copper deposits in the soil or in solution in the streams 
near by. On this account he has naméd it the ‘copper plant,” and 
notes also that in regions rich in copper it is the predominant member 
of the herbaceous flora. It is of interest in this connection to note 
that Lehman found that the tissues of fowls feeding in regions rich in 
copper yielded 15.5—115™* of this substance per kilo of dry matter. An 
investigation of the plants growing in the copper regions around Lake 
Superior, and near the dumping grounds of cities, would doubtless 
bring some interesting results as to the absorption of metals.—D. T. 
MacDovzeat, University of Minnesota. 
FROST FORMATIONS. 
THE purpose of this note is to collect the records of observations 
of frost formations on plants not included in my résumé in this journal.‘ 
A letter from Professor Trelease dated April 7, 1894 states that he 
had observed the formation of crystals of ice on Verbesina Virginica 
3Tin Mines of Watsonville, Rep. by J. B. Skertchly, Assistant Geologist, Queens- 
8 
*19:120. 1894. 
