390 



Plant Physiology 



The following table from Duvel indicates the average loss 

 of vitality of thirteen kinds of seed sent to seven different 

 localities in the United States and to Porto Rico, and 

 kept under ordinary conditions of storage, the first test 

 covering a period averaging 128 days (February to June), 

 the second period averaging 251 days (February to Octo- 

 ber) : 



The control seeds referred to in the table were kept in 

 a cool, dry closet in the botanical laboratory, Ann Arbor, 

 Mich., and these showed a remarkable vitality. 



231. Environmental conditions. Duvel determined 

 that under ordinary conditions moisture and temperature 

 are the more important factors. Rise of temperature 

 alone may not be injurious unless accompanied by in- 



