BOTANY: A. B. STOUT 
131 
garding the constancy of characters or of assumed factors of heredity, it seems 
very evident that critical studies of somatic variations, especially wherever 
it is possible to propagate vegetatively, are of fundamental importance. 
To Darwin, bud variations in plants were evidences of the very indiscrimi- 
nate variability that is everywhere present in organisms. Their broad signif- 
icance and range were recognized by his conclusions that they include: (1) 
reversions to remote ancestral characters; (2) reversions (in hybrids) to the 
more immediate parental qualities; and (3) cases of real spontaneous change 
in hereditary composition of continuous as well as of discontinuous range. 
Darwin did not believe in fixed hereditary units. 
These same types of bud variation are, in general, recognized by de Vries 
(1901). He attempts, however, to assign mutational value of discontinuous 
rank to the spontaneous somatic variations quite as he does to seed mutations. 
Yet he recognizes a wide variability and irregular hereditary performance in 
both. For example, he describes half races, middle races and eversporting 
varieties in the various steps in the development of varieties from pure species 
involving characters frequently concerned in bud sports and ascribes the series 
of changes to conditions of latency, semilatency, lability or activity of hered- 
itary units (pangens). To many critics of the mutational doctrines it is dif- 
ficult to recognize such spontaneous hereditary variations as discontinuous 
either from the facts or explanations presented by de Vries or by other inves- 
tigators. We may note further that many bud variations, such as the develop- 
ment of variegated branches on pure green stems were considered by de Vries 
as progressive mutations. 
In general, Cramer's (1907) classification of bud variations follows that of 
de Vries for seed mutants with, however, a greater emphasis on the operation 
of Mendelian segregations in certain groups. He recognizes, however, quite 
as did Darwin and de Vries, the occurrence of a large group of bud variations 
in which continuous and sporadic or eversporting variability is in evidence. 
The present day Mendelian studies of the seed progenies from bud variations 
and of characters exhibiting such variations show as a rule decidedly mixed and 
non-Mendelian results, or, at least, their interpretations involve subsidiary 
hypotheses. Some special tendencies in such interpretations may be noted: 
(1) the assumption that the transmission of certain characters is by the cyto- 
plasm rather than by the nucleus; (2) the assumption that somatic variations 
are losses of hereditary factors accomplished by qualitative or segregative 
cell divisions, and (3) the claim that hereditary factors may themselves sporad- 
ically change, and the new factors come to immediate expression by domi- 
nance, or remain recessive, or exhibit various influence as modifying factors. 
Thus in certain attempts to analyze the heredity of seed colors in varie- 
gated corn it is assumed that factors for variegated color can change recipro- 
cally in a series of somatic divisions and that as many as ten 'multiple allelo- 
morphs' may be present, which, as Jennings (1917) remarks, "leap back and 
forth from one character to another in bewildering fashion." 
