Kraus: Somatic Segregation 7 
consideration. It is of extremely com- 
mon occurrence and generally may be 
observed by anyone who will spend a 
short time in search for it. On the 
campus at Corvallis there appeared on 
one of the several hundred bushes of 
Portugal laurel, cultivated as an orna- 
mental, a green and white variegation 
which now represents fully one-third of 
the entire shrub. From the green and 
white shoots several which are entirely 
white have sprung, but, as yet, none 
which is entirely green. The same 
variegation in connection with the 
normal plant from which it sprang, has 
been observed in more than a score of 
widely scattered species; among them 
red clover, maple, dandelion (Taraxa- 
cum), carnation, radish, bean, ox-eye 
daisy, ash, holly and Trillium. Such 
green and white variegations are readily 
propagated vegetatively. Many orna- 
mentals also come to mind and furnish 
readily accessible material for study. 
On almost any individual it is possible 
to find shoots which are entirely white 
and frequently those which are entirely 
green. This behavior is clearly a case 
of segregation. The green shoots are 
readily propagated and, if left to remain 
on the plant from which they sprang, 
often outstrip the remainder of it in 
growth. The white form is generally 
vegetatively weak and usually is in- 
capable of independent existence. 
But to account for the original appear- 
ance of the “white” character. For- 
tunately we are in a position to know 
that the white exists as a recessive in 
some plants, as shown by Emerson in 
his work on maize. Chapin found, in 
the case of variegated Amaranthus, that 
seed from green branches produced 
green seedlings while self-fertilized seed 
from white branches produced white 
seedlings, which facts led to the con- 
clusion that the green and white 
variegated plants are the result of the 
crossing of green and white gametes. 
If, then, green and white gametes exist 
in the case of those variegated plants 
(hybrids) resulting from the cross be- 
tween them, the appearance of the green 
and the white shoots is a case of segre- 
gation resulting from hybrid ancestry. 
On the other hand, where the green and 
white forms spring directly from a form 
which always has been green, so far as 
recorded, the appearance of the white 
character probably would be considered 
as amutation. The question arises: Is 
there a difference between the green and 
white combination which arises as a 
mutation and that produced by crossing 
green and white gametes: Whether 
the variegated form arises in one way cr 
the other they are apparently indis- 
tinguishable. In either case entirely 
green and entirely white shoots are 
frequently produced in the same manner 
and may be similarly propagated. It 
is in instances of this kind that the line 
of demarcation between segregations 
and mutations is drawn only with 
greatest uncertainty. A further study 
of them may aid us also in arriving at a 
more definite knowledge of the nature 
of mutations themselves. 
Double flowers from single flowers, 
laciniated foliage, weeping and fasti- 
giate forms, purple foliage, and other 
less common variations are considered 
as mutations. It seems that, in general, 
many wide changes in the color of the 
flower should be classed as a segregation 
rather than a mutation, especially so if 
breeding records show the same colors 
among the progeny, though, even under 
these circumstances, how to _ distin- 
guish the two absolutely is a problem, 
since it may be argued that the appear- 
ance of new colors among the seminal 
offspring may likewise be due to muta- 
tion. 
Like true segregates, mutants may 
be perpetuated vegetatively, and scores 
of horticultural varieties exist. The 
exceptions to this rule are the pure 
white forms which soon perish when 
severed from the parent plant and may 
be budded or grafted into other stocks 
only with greatest difficulty. 
SUMMARY 
To sum up, then, vegetative varia- 
tions are first of all of two distinct sorts 
—modifications or fluctuations, which 
do not remain true when propagated 
and subjected to varying conditions, 
and segregations or mutations which 
may be propagated and expected to 
remain reasonably constant under a 
