24 
BULLETIN 195 ; U. S. DEPARTMENT OF AGRICULTURE. 
tuber, and also in the growth habit of the vine, were studied. The 
work of Fischer was very largely carried on in pots, under as nearly 
uniform conditions as it was possible to obtain, and yet the varia- 
tions in the yield of tubers were in some instances in the ratio of 100 
to 233.3. 
The individual deviation within the variety itself was found in the 
case of the Saxon onion potato to be associated with certain definite 
characters; for example, flat-round tubers rich in starch were found 
to be correlated with a more or less restricted vegetative growth and 
tuber yield. Long tubers poor in starch were, on the other hand, 
found to be correlated with strong vegetative growth and a high 
tuber yield as compared with that of the flat-round ones. This is 
strikingly shown in the following data, which give the relative pro- 
portion of dry stalks and tubers from the two types of mother tubers: 
I. Flat-round mother tubers rich in starch (18.68 per cent); dry stalks, 100; tuber 
yield, 100. 
VII. Long mother tubers poor in starch (11.83 per cent); dry stalks, 141.5; tuber 
yield, 204. 
The deviations within these types were also noted by Fischer, and 
data were presented (Table V), a study of which shows that, while 
considerable deviation existed within the two types, the maximum 
yield of the flat-round tubers rich in starch did not approach very 
closely either in weight of dry stalks or of tubers to that of the lowest 
yield from the long tubers poor in starch. 
Table V. — Individual deviations in the development of vine and tuber within the same 
strain of a variety. 1 
Strain 
No. 
Character of strain. 
Dry 
stalks. 
Tuber 
yield. 
Average gain of 
long over flat- 
round tubers. 
Dry 
stalks. 
Tubers. 
II 
Per cent. 
100 
114.5 
142 
175.5 
Per cent. 
100 
167 
216.7 
233.3 
Per cent. 
Per cent. 
III 
... do 
V 
Long tubers poor in starch 
} « 
VI 
do 
62.5 
1 Table compiled from Fischer, Max. Op. cit., p. 305. 
Fischer also noted that the plants from the flat-round tubers were 
shorter jointed and matured earlier than those from the long tubers. 
This would indicate that the latter represented a later maturing 
strain. • 
In December, 1904, Eustace 1 reported the result of a season's 
study on "Productive vs. unproductive hills." The method of 
selection pursued by Eustace was as follows: At harvest time in the 
1 Eustace, H. J. An experiment on the selection of "seed" potatoes: Productive vs. unproductive hills. 
In Proc. Soc. Hort. Sci., 1903-4, p. 6C-62, 1905. 
