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XVIII.— ON THE PEEMANENCY OF FBOST-MABKS, AND A 

 POSSIBLE CONNEXION THEREWITH WITH OLD- 

 HAMIA RADIATA AND 0. ANTIQUA. By J. JOLY, 

 B.E., Assistant to the Professor of Engineering, Trinity 

 College, Dublin. 



[Read, March 24, 1886.] 



The object of this note is more to draw attention to a line of 

 inquiry, possibly not unfruitful, than, with the present amount of 

 evidence, to demonstrate any hypotheses. The experiments neces- 

 sary to throw light on the hypothesis suggested demand more 

 time than I will for many months be able to spare. Some few 

 experiments have, indeed, been made, and, for more than a year 

 seeking for leisure to continue them, I have postponed bringing 

 the very simple matter before the Society. 



In the Christmas holidays of 1884, I, in company with some 

 friends, was engaged on a short excursion through the Co. Wicklow. 

 The weather was frosty, freezing at night, and thawing by day in 

 the sunshine. There had been rain, and the roads, where the thaw 

 prevailed, were soft and muddy. In this mud, just outside 

 Roundwood, we noticed very regular marks, evidently left by 

 the frost. The frost was gone, and the mud was soft and wet ; 

 but in ruts and empty pools, wherever a smooth surface obtained, 

 the frost had channelled its impress. The appearance was that of 

 tufts, regularly radiating from a centre in rays which straggled 

 over the slime in long tendrils, these being again often sub- 

 divided into more numerous tendrils. The effect produced so 

 closely resembled the tufted appearance of Oldhamia radiata, that 

 the thought was immediately suggested of the possible common 

 origin of the two, and I drew the attention of my companions to 

 the resemblance, which one of them, Mr. Crosthwaite, was well able 

 to appreciate, being familiar with the Oldhamia marks. 



Similar marks were subsequently met with in abundance that 

 day, and again noticed in Grlendassan the ensuing day. I have 

 since observed them after every frost. 



