EFFECTS UPON GERMINATION 815 



under such illumination. Gassner (25) showed that N compounds were 

 without effect in forcing the germination of N. saliva seeds. 



Liliaceae. —KinzQl (46, 47, 48, 50, 51) claimed that many seeds of the 

 family Liliaceae were favored in germination by darkness. Of the genus 

 Allium, seeds of the following species were favored by darkness: Allium 

 ascalonicum, A. cepa, A. moly, A. porrum, A. schoenoprasum, A. ursinum, 

 and A. victorialis and the seeds of A. sihiricum and A. suaveolens were 

 favored by light. Other dark-favored liHaceous seeds which Kinzel 

 investigated were: Aloe variegata, Anthericum liliago, A. ramosum, 

 Asparagus officinalis, Asphodelus ramosus, Eremurus rohustus, Fritillaria 

 impcrialis, F. armena, Funkia coerulea, F. sieholdiana, Lilium martagon, 

 Maianthemum hifolium, Medeola asparagoides, Paris quadrifolia, Poly- 

 gonatum officinale, Ruscus aculeatus, Streptopus amplexif alius, Tulipa 

 gesneriana, Urginea scilla (dried 2 weeks), Veratrum nigrum, and Yucca 

 aloifolia. Other light-favored hliaceous seeds were : Colchicum autumnale, 

 Convallaria majalis, Lloydia serotina, Narthecium ossifragum, Paradisea 

 liliasirum, Smilax aspera, Tofieldia calyculata, Urginea scilla (fresh), and 

 Uvularia grandiflora. Polygonatum verticillatum and Hyacinthus candi- 

 cans proved indifferent. The tests of seeds of the Lihaceae were made 

 under relatively limited conditions and in some cases only one test was 

 made. 



Other Seeds. — Many other seeds are inhibited by light under certain 

 conditions. This was true of C Moris ciliata at temperatures below 22°C., 

 while at temperatures above 22°C. hght favored germination. Baar (5) 

 found several seeds favored by darkness at low temperatures and by 

 light at high temperatures. Amaranthus caudatus seeds were light- 

 inhibited at 5° to 20°C., indifferent at 25° to 30°C., and light-obligates 

 at 35° to 40°C. 



EFFECT OF VARIOUS REGIONS OF THE SPECTRUM 



Considerable work has been done upon the relative effectiveness of 

 various regions of the spectrum in promoting the germination of light- 

 favored seeds and in lowering the germination of light-inhibited seeds. 

 Before studies in this field can be rationalized, it will be necessary to know 

 whether the effective action of hght is upon the coats which are largely 

 nonliving, the hving contents of the seeds, or both ; or whether all three 

 of these categories are represented in various light-sensitive seeds. Most 

 seed and fruit coats are colored, showing differential absorption of the 

 visible spectrum. If the endosperm and embryo alone are affected by 

 light, only light which passes through the coats and is absorbed by these 

 organs is significant. If the coats alone are affected, only light absorbed 

 by them is significant. If both portions are affected, both the light 

 absorbed by the coats and the hght passing through them are significant. 

 Unfortunately, most of the experimenters have not studied the action 



