72 THE AMERICAN BOTANIST 



for providing- bird food and is so intent on securing this 

 that some care has to he exercised to avoid stepping on her. 

 Early in the season, earthworms were apparently quite ac- 

 ceptible food, but with the advent of young ones, a decided 

 fondness for cutworms, wireworms, white grubs and May- 

 beetles was apparent and the earthworms were neglected. Of 

 the entire list of insects, the white grubs were first in favor. 

 Nothing else could induce the robin to feed from the hand, but 

 the sight of the squirming, fat, white grubs always overcame her 

 caution. The number of harmful insects that a single robin 

 will pick up in an hour is astonishing. Apparently the only 

 representatives of animal life left in our garden are the earth- 

 worms. The only point for concern in this, is that there may 

 possibly be nothing left to attract our bird another year, but 

 if this should happen we will import some. 



Twisted Stems. — A subscriber on the Pacific Coast 

 writes: "The other day when walking on the Marin County 

 hills near San Francisco a young engineer told me that 'the 

 lidges in the bark of coniferous trees follow a spiral about the 

 tree always toward the right. He pointed to a Douglas fir to 

 c< mfirm his statement and I could see a very slight tendency for 

 the lines to vary somewhat from the perpendicular toward the 

 right. I had never noticed it and fear I am somewhat skeptical 

 as to its being an invariable custom. Is this known to be a fact, 

 and if so, why ? In the high sierras I have seen dead junipers that 

 looked as though they had been twisted all the way around, but 

 thought that this might have been due to the constant winds." 

 At the tip of a growing stem, there is a group of cells which by 

 frequent division add to its length. The new cells formed are 

 at first much smaller than mature cells and increase in size by 

 lengthening and stretching. The lengthening process appears 

 not to occur simultaneously throughout the stem but follows a 

 spiral path, which in most plants might be described as winding 

 upward to the right. Why growth should proceed in this man- 



