256 Experiments in Physiological Botany. 



14th, there was no alteration in the stumps, the sap reached 

 nearly to the ground, and the upper wounds were encrusted 

 over with a nasty fetid mucilage. During the above eight 

 days, the weather was fine with a good deal of sun. Medium 

 of heat 61°, and of cold 40^ 



In the night before the 15th, the weather changed to a 

 sharp cutting wind, and the sap ceased to flow from any of 

 the most recent wounds. No alteration in the stumps or 

 trees till the evening of the 20th except a very slight exuda- 

 tion from the trunks of recently felled trees, which, when wiped 

 off, appeared to come from all parts of the wood, medulla, 

 and alburnum alike. Medium of heat those six days 52°, of 

 cold 41°. 



On the 21st and 22d, a little sap exuded from the most 

 recent wounds and felled trees, which was quite thick and 

 glutinous. Those two days were fine, with 64° and 66° of 

 heat. 



At this time, the strong roots would exude just sufficient to 

 moisten dry earth dusted on a recent wound ; and the extreme 

 ends of the fibrous roots looked white, just as if they were 

 beginning to grow. 



On the 23d, heavy rain and cold set in, and continued to 

 the 30th ; during which time I could not find the least change 

 in the young shoots, which stood at one, two, or three young 

 leaf joints, and about as many inches long, or did the roots 

 advance, no sap exuded from roots or branches. The me- 

 dium of heat in the last ten days was SOjVj and of cold ^2-^-^^°, 

 and 3to°o in- of rain had fallen. 



The observations were continued to the 4th of May, on 

 which day, all the standing trees, and stumps of the felled 

 trees, clearly denoted an extension of young wood and roots, 

 and a mucilaginous matter rested on the surface of all the 

 stamps with minute globules of air in and under it. Whether 

 the air was from the combined effects of rain, sap, and heat, 

 or came from the root stumps 1 could not distinguish. In 

 the last four days, iVo of an inch of rain had fallen in genial 

 showers ; and the medium of heat was 62°, and of cold 46°. 



This terminated these experiments ; but others had been 

 made with exactly the same results as to the primary motion of 

 the sap, and progress of vegetation : but, with regard to time, 

 there was a material difference; viz. a vine in a pot put into 

 a pine stove, on the 13th of March, completed the process in 

 eight days, and a small birch tree in a pot, put in the same 

 situation on the 5th of April, got through the same process in 

 rather less than five days. 



Yours, &c. 

 WelbecL Feb. 1. 1826. Joseph Thompson. 



