1921.] Influence of Size of Seed on Yield of Potatoes. 47 



result is in luiiinoiiy with a long series of unpublished experi- 

 ments, which, amongst other things, show that the crop of a 

 potato plant must be expressed in the quantity cf tuber material 

 produced, its subdivision into tubers depends on other factors 

 and is probably influenced by environment. The general 

 approximation of the numbers of tubers in the classes of the crop 

 from mixed seed, with that of the average of the eight seed 

 classes, is a fact of considerable interest. 



It will be remembered that seed class No. 8 consisted of large 

 tubers with secondary growths. A close scrutiny was made 

 throughout the crops of the 8 classes for tubers exhibiting 

 any tendency to similar outgrowths. In Table IV the percen- 

 tage of tubers thus affected in each class is shown. It will be 

 noted that so far from the crop of seed class No. 8 showing any 

 excess, it actually has by far the least of such tubers. It is, 

 moreover, the bigger tubers in each case which tend to exhibit 

 secondary growth at all. That the tendency to secondary growth 

 formation should not be conveyed is in full accord with a number 

 of more critical experiments the results of which will shortly be 

 published by the wTiter and Mr. J. W. Lesley. 



TABLE IV. 



! Percentages of Secondary Growth in each chiss of Tuber. 





















Under 1 oz. 



1-1.} oz. 



1^2-6 oz. 



3-4i oz. 



oz ami over 



1. 



0-44 oz. 







8-6 







10 2 



15-1 



2. 



1 -33 oz. •. 



2 



5 



4-75 



Id 35 



33 3 



3. 



2*0 0/.. 











8-7 



28-5 



370 



4. 



2-66 oz. 



2-5 







4-35 



6-25 



23-r) 



5. 



4-0 oz. 







2-85 



1-4 



8-3 



35-2 



G. 



5-33 oz. 







1 3-55 



51 







33-3 



7. 



5-66 oz. 









3-95 



14-3 



21-0 



8. 



6 oz. with outgrowths.. 







I ' 







2-75. 



8-0 





Average 



•5 ■ 



j 2-5 



3-53 



10-83 



25-8 



1). 



Mi.xeil Soed 











15-0 



13-9 



43-5 



It will be seen also, that there is no relation between the 

 amount of tubers with outgrowths in the same weight gi'oups 

 in the crops from the different seed classes, excepting that in 

 the small weight classes the proportion is uniformly low, whilst 

 in the higher ones it is very variable, but generally high. There 

 is here no such close relation between the values for the average 

 of the crops from the eight seed classes, and those of the groups 

 in the crop from the mixed seed as was found in respect of both 



