510 The Journal 
on the leaves are occasionally found on 
the keels of prophylla, though they are 
usually small and poorly formed. 
It was at first thought that the 
lobing of the leaves was a purely local 
abnormality directly due to some cli- 
matic disturbance much as is the leaf 
cut or Tomosis of Cotton. However, 
the observations of Blaringhem in 
France and Gernert in Illinois demon- 
strate beyond doubt that forms of 
lobing have a wide distribution.! In- 
vestigation also shows that lobing not 
only occurs on experimental varieties 
outside their natural environment, but 
is found in about the same percentage 
in commercial plantings in many lo- 
calities. 
The cause of the lobing was not fully 
understood until in dissecting some very 
small lateral branches of Euchlaena 
it was noticed that several of the shoots 
were prevented from unfurling by 
having the margins of one of the leaf 
blades firmly held together with lobes. 
By examining still smaller shoots, the 
stage was finally reached where the 
lobes were just being formed. These 
shoots were about 6 cm. long and the 
tissue was exceedingly tender. It was 
at once seen that the lobes were formed 
by the margins of the leaf blades cutting 
“ach other where they crossed in 
unfurling. ! 
The forcing of the inside margin of 
the leaf against the outside margin 
results in the inside margin being cut, 
but at the same time the outside 
Mutations 
It has sometimes been alleged that 
the characters of wild species of potato 
are immutable, but J. Aumiot, who has 
been breeding many of them, reports 
changes of many kinds, in C. R. Acad. 
Agric., November, 1915, summarized 
in the International Review of Agricul- 
ture. Aside from changes of simple 
characters like color, there were sup- 
et Traumatismes (Paris, 1908). 
of Heredity 
margin also receives a slight cut through 
which the lobe on the inside margin 
grows. As this lobe grows it cuts up- 
ward into the outside margin which 
accounts for the small back cut some- 
times found on one margin of the more 
perfect specimens. A slight rupture of 
the tissue, which at this young stage is 
extremely tender, results in the sepa- 
rated cells developing practically inde- 
pendent of the remainder of the leaf 
blade. 
The fact that the two margins of the 
same leaf mutually rupture each other 
accounts for the lobes being most often 
found in pairs one on each side of the 
leaf. 
Lobes are not always made by the 
margins of the same leaf, but are 
sometimes made by the margins of 
adjoining leaves. In this way a single 
lobe on only one side of the leaf is 
brought about. Frequently when the 
margin of a leaf comes in contact with 
another leaf immediately inside of it 
the result is an opening in the leaf 
which develops marginal tissue on each 
edge. The marginal teeth, if examined 
at an early stage, are seen to be about 
half the size of the teeth on the outside 
margins of the blade. 
The comparatively late stage in the 
development of the leaf at which lobing 
takes place, demonstrates that the 
cells normally forming the body of the 
leaf blade are capable of being trans- 
formed into the specialized marginal 
tissue. 
in the Potato 
posed mutations which affected the 
time of maturity, the character of the 
skin, the growth habit, and the flowers. 
In one instance a plant of Solanum 
commersont is alleged to have been 
transformed so that it closely resembled 
a cultivated variety. The study of such 
cases as this might throw much light 
on the process of evolution. 
' The first notice of these lobed leaves which I have found is by L. Blaringhem in Mutation 
Blaringhem mutilated maize plants in various ways and then 
grew their seed; the resulting plants showed various abnormalities, such as cleft leaves, which he 
thought were due to his mutilation of the parents. 
When other observers discovered the same 
abnormalities in maize plants whose parents had not been mutilated, Blaringhem’s effort to revive 
the inheritance of acquired characters came to nothing. 
Since the *n Gernert mentioned lobed or 
cleft leaves as one of the many abnormalities to be found in maize, but gave no explanation of 
their origin. 
25, Champaign, IIl., 1912.) 
(“The Analysis of Characters in Corn and their Be havior in Transmission,” p. 
y 
