468 proceedings of the academy of [may, 



Conditions Influencino the Growth of White Cedar 

 AND its Parasitic Fun(4I. 



The temperature of sphagnum bogs is well kuown to be low, and 

 the expression cold bogs is frequently met with in the descriptions 

 in the manuals. European students Of bogs consider the low 

 temperature as due to evaporation from the surface of the sphag- 

 num which grows in the bogs, but this seems altogether inadequate 

 to explain the phenomenon. Ganong" supposes it to be due ratlier 

 to a persistence of the winter cold, which in such a non-conducting 

 mass would last through the summer. In this explanation the 

 writer entirely agrees with Prof. Ganong, although in Xew Jersey 

 the winter cold does not persist throughout the entire summer. 

 One ivould expect this from the more southern position of New 

 Jersey, as compared with the northern latitude of New Brunswick, 

 there being a difference of six degrees of latitude between the two 

 stations. The difference in latitude hardly expresses the difference 

 in climate, because of the exposure of New Brunswick to the 

 descending polar currents. "It is easy to test these two hypo- 

 theses ; for if the former be true there should be little change in the 

 temperatui'e conditions after the summer average is once attained, or 

 ev^en the bog might be somewhat low^er in temperature when the 

 season is hottest, and hence evaporation most active ; if the latter 

 be true the bog should steadily rise in temperature through the 

 summer." Ganong took the temperature of the bogs studied by 

 him and found that there was a perceptible rise of temperature 

 during the summer, the temperature rising in two months an aver- 

 age of 2° at one foot under the surface. The same author found 

 on July 1, near the centre of the bog observed by him, sheets of 

 ice six to eight inches thick and several feet square about a foot 

 under the surface. 



All of these facts are of interest in connection with the character 

 of growth of the white cedar. The persistence of the uniform 

 temperature, i.e., the slow heating up of the soil and water of the 

 swamps, regulates to a remarkable degree the character of the 

 annual rings of wood. With rapid growth in the wet spring, 

 ordinary dicotyledonous trees, as a rule, have well-defined spring 

 elements with usually wide open lumen. As the summer advances 



'^ Ganong, Upon Raised Peat Bogs in the Province of New Bruns- 

 wick, Transactions of the Royal Society of Canada, 2d Ser., Ill, p. 151. 



