224 SCIENCE REMAKING THE WORLD 



ing the combined efforts of many scientific specialists. 

 What are a few of these problems and how are they 

 being studied ? 



THE REST PERIOD. In order to insure the con- 

 tinued vegetative propagation of the potato plant as a 

 permanent inhabitant of the earth, nature has en- 

 dowed the tubers with a rest or dormant period, so that 

 the young plants will not immediately start to grow and 

 then be killed by the coming winter cold. This is fine 

 for the wild plant, but since man has tamed it and 

 brought it under cultivation, the operation of the rest 

 period does not always suit his requirements. Usually 

 the potato tubers will not sprout for several weeks after 

 they are harvested. The length of the rest period varies 

 with different varieties, but is fairly constant for a given 

 variety grown for a long time at the same place. The 

 cause and control of this rest period is a subject of im- 

 portance. Any practical means of eliminating or even 

 abbreviating the rest period would be very valuable in 

 growing a second crop in our southern states. It is 

 also of equal importance to know how to extend the rest 

 period of potatoes during storage. So far scientists 

 have not been able fully to unravel nature's secret of 

 dormancy in potatoes, but some clues have been ob- 

 tained. By carefully removing the skins from the 

 tubers and supplying them with plenty of moisture, 

 air, and a certain amount of warmth, the young sprouts 

 will start to grow in a comparatively short time. This 

 seems to indicate that the skins keep out something 

 necessary for growth or prevent the escape from the in- 

 side of the tuber of something holding growth back* 



