528 
R. RUGGLES GATES 
organism, but especially in the buds. When the chemistry of the 
nucleo-proteins is better known, it may be possible to determine what 
chemical change one of them would have to undergo in order to in- 
crease the amount of anthocyanin produced by interaction with the 
cytoplasm of the cell, but these matters are as yet too complex for 
analysis, though much is being learned concerning the chemistry of 
anthocyanin and the physiology of its production in the cell. 
Like the morphological mutations to which reference has already 
been made, there can be little doubt that Oe. ruhricalyx is also a cell 
mutation, the nuclei in all parts of the organism containing a de- 
scendent of the original changed chromosome. Parallels to this 
mutation are found in such plants as the copper beech and the red 
sunflower, which belong to widely separated groups. 
In conclusion, our complete lack of knowledge of the relation 
between internal cell structure and external form in organisms may 
be pointed out. Except in the relatively simple case of gigantism 
through tetraploidy it is quite unknown how a change in the nucleus 
of the cell-unit results in the external modification of characters. 
Why are the buds of Oe. ruhricalyx more conspicuously red than any 
other part, and why are the leaves of Oe. lata blunt, the buds rounded, 
the pollen sterile, etc.? Before an answer to such questions can be 
attempted, something must be learned of the way in which the meta- 
bolism of the cell — a complex series of chemical activities^ — expresses 
itself in the form of structure involving relationship between differ- 
entiated cells and tissues. 
which is a recessive, the grayness results from a structural modification in the canals 
which connect the pigment-producing cells with the hair follicles, rendering them 
too narrow for the passage of the pigment granules. 
