24 



BULLETIN 195, U. S. DEPARTMENT OP AGEICULTUEE. 



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 sta:lks, 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.^ 



strain 

 No. 



Character of strain. 



Dry 

 stalks. 



Tuber 

 yield. 



Average gain of 

 long over flat- 

 round tubers. 



Dry 

 stalks. 



Tubers. 



II 

 III 



V 

 VI 



Flat-round tubers rich in starch 



do 



Long tubers poor in starch 



do 



Per cent. 

 100 

 114.5 

 142 

 175.5 



Per cent. 

 100 

 167 

 216.7 

 233.3 



Per cent. 



Per cent. 



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 ^ 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. 60-62, 1905. 



