[Vol. 2 



272 ANNALS OK THE MISSOURI BOTANICAL (-AKDEN 



that special stimuli might be applied to such cells in a maimer 

 that might bring about similar results. Practically, however, 

 it would be enormously difficult to localize initial cells with 

 sufficient certainty so as to give any slight chance of success. 

 The second stage of germ-plasm in which it is in the form 

 of sexually specialized elements oilers far more promising 

 conditions for experimental modification of the genetic con- 

 tent of the species which it represents. Solutions may be in- 

 troduced into the ovaries in such manner as to affect the egg 

 bearing the entire group of qualities of the species, and fur- 

 thermore the direct action of such reagents may be ascertained 



to some extent. 



The present-day aspect of the mechanism of heredity is one 

 which increases momentarily in complexity. The greater part 

 of the researches in genetics during the last fifteen years has 

 been devoted to the interaction of factors, determiners, in- 



hibitors, or qualities in the organism. If these conceptions 

 may be taken to be the expression of the reactions of either 

 chemical groupings or to rest upon a physico-chemical founda- 

 tion of any kind, the reagents which have been used have not 

 been of a selective character, but would affect practically the 

 entire colloidal mass of the protoplast in some manner and to 

 varying extent, neutralizing or coagulating proteins, and their 

 general tendency would be to inhibit or check energy trans- 

 formations. In the case of the iodine treatments the free ions 

 from potassium iodide or the iodic acid formed would cause 

 a neutralizing effect, as it does not seem from the results of 

 Czapski and Adler 1 that this element would form any com- 

 pound with the proteins. 



The experimenter is dealing with an actual physico-chemical 

 complex of highly unstable compounds in which many types 

 of energy transformation are occurring. Introduced sub- 

 stances may slow down or inhibit some of these, and accelerate 

 others or start new reactions. The morphological possibili- 

 ties in any given strain of plants are somewhat limited, how- 

 ever, and in this sense the direction of the departures is al- 



1 Beitriige zura Chemismus der Jodwirkung. Biochem. Zeitachr. 65:117. 

 1914. 



