226 BOTANICAL GAZETTE [SEPTEMBER 
age of the leaf; besides, these leaves turn brownish yellow on the applica- 
tion of iodin and therefore do not show clearly the reaction with starch. 
Ficus elastica requires more than one day to make a perceptible amount. 
Only very young leaves of Primula obconica, Primula sinensis, and Cinera- 
ria cruenta can be emptied of starch; being stemless plants, they probably 
use the older leaves for its storage. Young plants of Pelargonium domesti- 
Disavprap- segs ea Sad fee 
NAME OF PLANT Retintag lt (T. 20°-25°C.) IopIN TEST 
: DARKNESS 
(T. 18°-22° C.) Perceptible fig. Good fig. | 
nights and days minutes minutes minutes 
PINNUOasiiat oe er oo ce 2 I 30 120 es 
Begonia coccinea........... 3 3 60 240 
B ca oleracea...) ... 2s. ° 20 5 5 
Cineraria cruenta (young Is)| 5 4 45 180 3° 
Coleus Blumei............. I 30 5° 36 
Cucurbita Pepo............ I ° 15 5° as 
Euphorbia pulcherrima 2 I 60 240 
Fuchsia speciosa........... I ° 45 9 15°95 
Helianthus annuus......... I ° 30 120 
Heliotropium peruvianum I ° 45 120 s Bie 
Impatiens Sultani.......... I ° 30 120 
Lupinus albus............. I ° 60 240 
alis Bowiei............. I ° 45 240 petits 
Pelargonium domesticum...| 2 I 5° 240 4 
Pelargonium peltatum...... = 2 50 270 = 
Pelargoni rto x : 
OMS 2 I 20 5° ~_ 
Phaseolus vulgaris......... I ° 20 oe 5 ° 
Primula obconica (young Is). 5 4 120 240 s* 
Primula sinensis (young ls) . 4 fe 45 120 
Raphan se ea fe) 35 6 3 
Ricinus communis... .... I ° 20 60 oss 
Salvia involucrata.......... 2 I go I20 ait 
Salvia splendens........... 3 2 30 60 =e 
Senecio mikanioides....... . I ° 20 5° 5 
Senecio Petasitis........... 3 2 30 180 25 
Tropaeol 1 Rear tis 2 I 50 ge ; 
Wels Pathe cates: I ° 60 240 = 
Cl TMI ss 3 2 30 120 5 
cum empty their leaves of starch in about 40 hours, but older p _ - 
unsatisfactory, because, even after 4 days in darkness, there are ant d 
of starch in the mesophyll. All these plants, except Oxalis Bowtet, er 
the young plants of Pelargonium domesticum, require 3 to 5 days in darkm 
—too long a time for the subsequent good of the plant. First 
Prolonged darkness produces two distinct deleterious results. : 
some plants, as Heliotropium and Impatiens, after 3 or 4 days in ose 
drop their leaves, owing to some derangement of their mechanis™, 
