59 



of the ribbon and wen- of clear, transparent ice. The ribbons, 

 themselves, were translucent; a difference which may be due in 

 part to the minute corrugations noted by Mr. Jennison. Small gas 

 bubbles were noticeable in the ice also. Another interesting fact 

 is that where the stems were cut they were still firm and woody. 

 The inner bark was green and appeared to be in a living condi- 

 tion; a circumstance which lends support to the assumption — 

 by Mr. Jennison — that the roots are still active. 



It is interesting to note that successive crops of crystals may 

 form on one stem although they retreat toward the base as the 

 stem is split by the ice plates. Their formation under the fallen 

 leaves also confirms the previous assertion that the water is 

 crystallized before it is forced from the stem. It is probable that 

 such formations occur often under cover and are not noticed. 



These "frost flowers" suggest a number of interesting prob- 

 lems. If they can be reproduced under controlled laboratory or 

 field conditions, careful study of them may lead to more exact 

 determinations of critical temperatures, root pressures in dor- 

 mant plants and other physiological and anatomical factors which 

 determine the frost resistance of hardy species. Careful analysis 

 of the gas bubbles enclosed in this ice and of the ice as well may 

 tell us something of the rate of and conditions attending respira- 

 tion in the roots of dormant plants. 



Lebanon, Tenn. 



