xxvm 



BOTAIJJT. 



was noticed, in a dead branch, eight inches in diameter, apparently of Pinus 

 monophylla, found in the East Humboldt Mountains. Here the decay of the 

 bark and drying of the wood revealed very plainly the course of the fibres, 

 which in a length of seven feet made four complete circuits. In some por- 

 tions the direction was very nearly at right angles to the axis of the branch, 

 and the length of the outer series of fibres must have been at least ten feet. 

 An opportunity was oifered at the saw-mill in Ruby Valley of ascer- 

 taining the age and dimensions of several specimens of Pinusjlexilis from the 

 upper canons of the East Humboldt Mountains. The following table gives 

 the length and end-dimensions of the "cuts," and the width of each series of 

 fifty rings from the outside toward the center. A comparison of these last 

 measurements shows great uniformity of growth in the different periods, in- 

 dicating a like uniformity in the conditions of temperature and moisture. To 

 these are added a few measurements of Arte7nida tridentata and Purshia, 

 also made in Ruby Valley, besides which may be mentioned a Juniperus 

 occidentalis twelve inches in diameter with 250 rings and a Cercocarptes ledi- 

 folius about two feet in diameter with 160 rings. 



Measurements of Tree and Shrub Grmvth. 



When the canons in the mountains are dry the vegetation in them differs 

 little from that of the intervening ridges, but in the presence of moisture 

 and especially upon the sides of the higher canons there is frequently a con- 

 siderable amount of shrubby or perennial herbaceous growth. The most 

 common species are Ceanothus velutinus, forming dense and tangled patches at 

 an altitude of from 7,000 to 9,000 feet, Rihes cereum scattered over all the 



