98 BOTANICAL GAZETTE , [February 



Gutzeit (5) repeated Aderhold's work and found by a rather 

 extensive set of experiments that exposures to temperatures below 



■ 



zero had no effect on stem or shoot production in kohlrabi, beets, 

 or various other plants. He did find, however, that a period at 

 +4° C. during germination and early growth caused about 30 per 

 cent of certain beets to produce shoots very early the first year. 

 Some of the shoots produced only very short stems, and the plants 

 were otherwise normal, while other shoots grew continuously and 

 early produced flowers and seeds. Beets of exactly the same kind 

 when kept at +22 C. during germination and early growth showed 

 no shoot production the first year. Only such beets as were pre- 

 disposed to early shoot production could be thus forced by low 

 temperatures, so hereditary characters as well as temperature enter 

 in as determining factors. Gutzeit suggests that this temperature 

 response explains why early seeding of beets causes much premature 

 shoot production, whereas late seeding gives little or none. On 

 the basis of other experiments conducted by himself, as well as 

 data from the literature, Gutzeit concludes that low temperatures 

 during germination and early growth favor stem formation, while 

 high temperatures at this time inhibit stem formation. 



Appel and Gassner (2) noted in the experimental fields of 

 summer cereals at the Agricultural Experiment Station at Dahlem, 

 Germany, a peculiar sickness, the plants becoming light green, and 

 the older leaves turning yellow. Since neither animal nor plant 

 pests seemed to be attacking the cereals, an explanation for their 

 condition was sought in unfavorable soil and weather relations. 

 Greenhouse experiments conducted by Appel and Gassner led 

 them to attribute the peculiar conditions of these summer cereals 

 to a too high germination temperature. 



They grew barley in pots in the greenhouse, keeping one lot at 

 25 C. and the other lot at 5-7 C. When the plants at the 

 higher temperature had reached a height of 15 cm., those in the 

 cool house had just come up. Both sets were then transferred to 

 the open and kept under like conditions. After three weeks the 

 barley plants from the warm house began to show signs of injury, 

 the older leaves yellowing at their tips, and only the youngest 

 leaves remaining green. The barley plants from the cool house 



