718 Miller.—A Physiological Study of the 
roots begins to increase in amount and reaches the maximum in the ten day 
seedling. 
The changes which the oily reserves undergo in the progress of the 
development of the seedling are difficult to determine. This is due to the 
fact that these reserves in seeds are composed of a mixture of glycerides 
which have never been separated from each other, and to the lack of know¬ 
ledge of the exact structure of some of the acid radicles of these glycerides. 
Nevertheless, certain processes and results can help in a measure to throw 
some light upon the changes which take place in germination. 
The value of the iodine number of the ether extract during different 
stages of germination gives one an idea whether or not the unsaturated acids 
are becoming saturated. The iodine number of the ether extract of the 
Fig. 17. Ether Extract, grams per 100 seedlings. 
cotyledons shows a gradual decrease in value during the progress of 
development of the seedling. The value decreases from 136-2 for the ether 
extract of the seed to 67-4 for that of the thirteen-day seedling. The value 
for the last two stages examined may be a little too low owing to the 
chlorophyll present in the ether extract, but the value of the other stages is 
not influenced by this pigment. The decrease of the iodine number seems 
to indicate that the unsaturated acid radicles of the oil are becoming 
saturated, probably by the addition of oxygen. Von Fiirth found no such 
evidence of a decrease in the value of the iodine number of the oil of the 
seed and seedling of the sunflower. His determinations, however, were 
limited to only one stage of the seedling, and cannot be given the same 
weight as the extensive work of Schmidt on the fatty acids of the sunflower 
