1921] GARDNER—GERMINATION 251 
but rather to its effect on the enzyme activity in the production 
and digestion of stored foods. RAcrBorskt (43) found that tobacco 
seeds germinate in diffused light after 1-5 hours’ illumination, a 
longer time being required if the intensity of light is low. In 1900 
TAMMES (49) declared that the exposure of dry seeds to direct 
sunlight did not affect their later germination, and in 1902 LAURENT 
(29) made the same statement. REMER (44) reported that light 
hinders the germination of Phacelia tanacetifolia, but offered no 
explanation of the light relations. LascuKe (28) confirmed earlier 
results with Poa, and stated that light cannot be replaced by 
higher temperatures. In the same year Ficpor (10) made a report 
on the influence of light on the germination of seeds of Gesneriaceae. 
In 1912 he (11) reported that seeds of 12 species of this family are 
favored by light. In 1908 Bessey (3) found that seeds of the 
epiphytic Ficus aurea and F. populnea germinate only in light. 
K4NzEL (24) in 1907 reported that the germination of freshly 
harvested seeds of Nigella sativa was prevented by light, while 
similar seed germinated up to 94 per cent in darkness. Even three 
minutes’ illumination after 24 hours’ incubation in darkness had a 
marked retarding effect. He considered the effect of light as photo- 
chemical, and designated such seeds as “light hard.” The germina- 
tion of some light-sensitive seeds in darkness was hastened by 
soaking in a solution of an enzyme such as papayotin (25). He 
(26) also published a long list of light-sensitive seeds, to which still 
others were added in his later work (27). He recognized as 
important factors in germination of seeds age of seed, character of 
seed coats, and color of light. LEHMANN’s work (30, 31, 32; 33) 34); 
begun in 1909, continued through 1915. Most of his experiments 
were conducted with seed of Verbascum Thapsus, V. thapsiforme, 
Epilobium roseum, and Ranunculus sceleratus. He showed the 
effects of substratum on germination in light, found the age of 
seeds to be an important factor, used Knop’s nutrient solution as 
a stimulus instead of light, and found that salts favored germination 
of light-sensitive seeds in darkness. He claimed that light exerts 
its influence by starting or stopping some chemical changes in the 
seed, and established a relation between light and temperature. 
He also punctured seed coats as a substitute for light. LEHMANN 
