22 GENETICS IN RELATION TO AGRICULTURE 
and six distinct types were found, according to the variation in number 
of stamens. These had the following average numbers of stamens: (1) 
9.68, (2) 8.45, (3) 6.54, (4) 5.05, (5) 9.47, (6) 7.33. Finally, Klebs 
subjected similar plants from white, red and blue light to chemical 
analysis in order to secure further evidence of the physiological effects 
of light of different wave lengths. Table I shows the composition 
of the leaves in three plants like those shown in Fig. 4. They were in 
their respective greenhouses from June 6 to September 7. The percent- 
ages shown are per 100 g. of 
dry substance. In compar- 
ing these percentages it 
should be remembered that 
TaBLe I.—CHEMICAL COMPOSITION OF THREE 
Puants or Sedum Spectabile GRowN IN 
Wuitsr, Rep anp Buiue Lieut. 
Substance White Red Blue the plant in white light pro- 
whee duced 1324 flower buds and 
ASs rua ieee en: 13.20 13.20 18.60 the plant in red light 405, 
DUP AG orcs enema ee: 11.04 15.40 2.40 ; : : 
Calcium malate. .... 22.29 18.02 18.10 while the plant in blue light 
Free nitrogen....... 0.16 | 0.33 | 0.59 produced none. This ex- 
Starche «sc 22 4! “5282 3.66 1.20 plains the higher percentage 
Crude protein...... | 5.33 6.15 7.64 of ash, nitrogen and protein 
in the last. On the other 
hand, the amounts of starch and sugar found in the plant from 
white light are decidedly larger than the one from blue light. In 
short, according to Klebs, in comparison with normal white light, 
the production of organic substances, such as starch and_ sugar, 
is diminished under the influence of blue light as microchemical 
and macrochemical tests distinctly show. In consequence of this di- 
minished assimilation of carbon dioxide the rosettes become purely 
vegetative. In red light the carbon assimilation is greater than in blue 
light but less than in white. These experiments prove that the transfor- 
mation of a plant “ripe to flower” into a vegetative one is possible on 
the one hand by an increase of temperature and of inorganic salts and 
on the other hand by a decrease of carbon assimilation. 
(b) Temperature and Pigmentation—Many experiments in the rearing 
of moths and butterflies under controlled temperatures prove that degree 
of pigmentation is profoundly influenced by the temperature at which 
the pupx are kept. Some species exhibit seasonal dimorphism in the 
wild state. By taking pupe of the common European form of the 
swallowtail butterfly, Papilio machaon, and subjecting them to a tempera- 
ture of 37° to 38°C., Standfuss obtained the characteristic summer form 
which occurs in Palestine. Again it has been shown by temperature 
experiments that many variations found among insects in nature are 
merely aberrations due to temperature effects. Goldschmidt by arti- 
ficially controlled temperatures has produced a series of forms of the 
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