154 FRO.n BLOMIDON TO SMOKi'. 



(i. e. unelaborated) than of the latter (/. e. elab- 

 orated), I should say. If he penetrates to the 

 cambium only he would get elaborated sap 

 (wliich is being transformed into tissue), and if 

 he peneti-ated the soft inner bark only he cer- 

 tainly would get elaborated sap flowing down- 

 ward, and probably that only. If it is elaborated 

 sap he wants, he would do much better to go 

 no further than the inner bark and cambium. 

 The medullary rays are so small in proportion 

 to the size of a woodpecker's bill and tongiie 

 that he would receive but poor wages for his 

 labor in penetrating them. Of course in spring 

 before the leaves are fully out, the sap is very 

 rich as it flows up, both in starchy and albumi- 

 noid matters, and then it would be worth working 

 for. But as late as July and August, the upward 

 flowing saj), while it contains traces of these nutri- 

 tious substances, must be veiy poor in them. 



" I never thought of the question before, be- 

 cause I did not know that woodpeckers bored 

 for sap. I always supposed it was insects and 

 their larvae they were after." 



SUMMARY. 



From these observations I draw the follow- 

 ing conclusions : that the yellow-breasted wood- 

 pecker is in the habit for successive years of 

 drilling the canoe birch, red maple, red oak, 



