114 
stalks of heliotrope and thistle. Prof. John Leconte made an 
extended study of the frost crystals of Pluchea camphorata and 
P. bifrons, in 1848, along the coast of South Carolina and 
Georgia.” Prillieux in his investigations on freezing in intercell- 
ular spaces described the formation of radial ice plates by herb- 
aceous plants.* These observations were duplicated by Trecul at 
the same time, and Sachs has given some matter bearing upon 
the frost freaks of the dittany are a matter of common informa- 
tion in the locality in which his observations were made.” 
In these accounts there are two points which seem signifi- 
cant. First, the occurrence of the phenomenon was either in the 
late fall when it is quite possible that the lower or root portions 
were not entirely dead; or, if later in the winter, they were re- 
ported from the southern states, where there is still a chance 
that the roots might be living. The second point (if we refer 
to the broad plates) is the remarkable restriction of the phe- 
nomenon to only a few kinds of plants. Cunila, Pluchea, and 
Verbesina, in whatever part of the country they may be, are 
almost the unanimous choice of the “frost flowers.” It is cer- 
tainly significant that with the thousands of herbaceous plants 
available these should be the ones selected. 
In view of these facts one would think that, as Professor 
Jennison says, the roots are still alive and functioning (a matter 
that could be easily verified by microscopical examination) and 
secondly, that these particular genera, in addition to possessing 
roots tenacious of their vitality, have stems which are peculiarly 
brittle, splitting easily in a vertical or length-wise direction, 
perhaps coincident with some corresponding arrangement of the 
xylem, so that the water forced up the stem, on reaching the 
Outer portions, freezes and splits the bark, the ice thus formed 
being pushed out by newer ice layers formed within, essentially 
as Prof. Jennison explains it. Anatomical and microscopic 
studies could doubtless clear up the whole question, if indeed, 
this has not already been done. 
A. H. GRAVES 
ë London and Edinburgh Phil. Mag. —: 110. 1833. 
7 Proc. sA. 9. 1880. 
* Compt. Rend. 70: 405. 1870. 
* Lehrbuch. 2 Aufl. p. 614, 
° Bot. Gaz. 19: 40, 1894, 
