Crystals of ice on plants. 
J. CHRISTIAN BAY. 
That ice crystals are formed on the surface of plants under 
certain conditions of weather and surroundings, as has been 
noticed lately by Profs. L. F. Ward and D. T. MacDougal, 
is by no means little noticed. In the winter and spring of 
1892 and 1893, these crystals were not unfrequent in Tower 
Grove Park and the adjacent fields in St. Louis, and I ob- 
served this phenomenon also in Europe, in the Botanic Gar- 
en, Copenhagen, as far as I remember, in the winter of 
1887-88, 
_ Supposing that the phenomenon has been sufficiently out- 
lined by the two first named observers’, I add the following 
references to those named by MacDougal.? 
_ James D. Dana mentions? that he has found, on cold morn- 
ings in spring and autumn, thread-like ice-crystals appended 
vertically to the stems of trees. Papers concerning the same 
subject are: 
R. Caspary, Auffallende Eisbildungen auf Pflanzen. Botan. 
Zeitung 12: 665. 1854. H. HoFFMANN, Pflanzenklimatologie 
329. 1857. HuGo Von MOL, Botan. Zeitung 18: 15, 16. 
1860. J. Sacus, Krystallbildungen bei dem Gefrieren. Be- 
richte d, kgl. Siichs. Akad. d. Wiss. zu Leipzig. Math.- 
Phys. Cl.—:1. 1860. C. N&GELI, Ueber die Wirkungen des 
Frostes auf die Pflanzenzellen. Sitzungsber. d. Miinchener- 
cad. d. Wiss. Math.-phys. Cl., 9 Februar, 1861. 
The communication of Sachs is, of course, classical. It 
should be remembered that H. de Vries and H. Miiller-Thur- 
§au have also been working with the influence of cold upon 
Plant cells; likewise Goeppert. 
a Plants on which ice-crystals have been observed. 
Conyza 
ton sp. [Herschel, 1833 
1854.) Topium sp. [Herschel, 1833.]; H. peruvianum (Bouché and Caspary, 
eee ee min yaar tad 
arly fen wu ee 35". 29 D 1893. 
rterly Bull., Univ. of Minn. 2: 30-31. 
Mineralogy, 46. Ed. 2, New Haven and Philad., 1849. 
1 
2er ae. Gaz. 18: 183. 189 
* Manual 
it L. (Pluchea bifrons DC.) [S. Elliott, 1824.] Waly Mei ront 
