THE AMERICAN BOTANIST 37 



twenty feet rind a diameter of two inches. The most aston- 

 ishing feature of the plant are the giji^antic berries which at- 

 tain a (Hanieter of two inches. Some of the berries are large 

 en<iu^h til ci>\cr a silver dollar. I'nlike certain gigantic 

 hlaikherries from other parts of the world the fruit-- "i this 

 >[)ecies are said to be very juicy and of good fla\'or. It i> 

 likely that it will he introducetl into cultivation in the cool, 

 moist regions along our Pacific Coast. 



Cold and Dokmaxcv. — From experiments recently car- 

 ried on by Government botanists, we may discover why it is 

 that hardy plants brought into the house in autumn will not 

 renew their growth, while the same plants left in the ground 

 until the}- have been exposed to freezing temperatures for a 

 time, will resume growth at once- It is the custom of tiiose 

 who grow rhubarb for the early market, for instance, to dig 

 up the plants and allow them to freeze before, starting them 

 to grow. In some of the experiments referred to, other plants 

 when kept from the cold remained dormant for an entire year. 

 Other experiments showed that the effects of cold are felt only 

 in the parts exposed to it. Plants were grown in such a w-ay 

 that part of the plant was exposed to the cold and part kept 

 warm and when the whole plant was then exposed to w'armth, 

 only the part exposed to the cold grew. The theory upon 

 which this peculiar behavior is accounted for is that grow^th 

 does not begin until some of the starch stored in the cells has 

 been turned to sugar. The enzyme that converts the starch 

 to sugar is supposed to exist outside the plant cells and to be 

 unable to penetrate into them until the cell wall has been weak- 

 ened in some way, as by freezing. Support is lent to this 

 theory by the fact that \arious injuries to the plant, such as 

 rubbing the hark, girdling, pruning or notching the stem, pro- 

 duce results similar to those produced by the cold. When 



