WOODHOUSE AND TAYLOR. 121 



That each variety contains unit species which differ in 

 their nitrogen and oil content from the mean of the variety is 

 not only extremely unlikely but is negatived by certain experi- 

 ments made by us on certain seeds which were found to differ 

 widely from the normal (vide Tables I, II and III). 



It will be seen from what has gone before that the variety, 

 having a high oil content had a low nitrogen content, and that 

 the contrary was also the case. This led us to wonder whether 

 the differences observed in 1910 and more carefully in 1911 

 might have been clue to some external cause which increased the 

 formation of nitrogen and at the same time decreased the 

 formation of oil. If this were the case the correlation between 

 nitrogen and oil content in any single variety should have a very 

 high negative value. The correlation was in consequence worked 

 out in each variety by the usual formula. 



The results in each varietv were very similar in magnitude. 

 They were as follows : — 



There is therefore an indication of a slight negative correla- 

 tion between the nitrogen and oil contents, but from these data 

 they cannot be considered to be complementary to one another. 

 In other words it is extremely improbable if, by some external 

 cause, we were to be able to increase the average nitrogen 

 content of the yellow soy bean crop until it reached the average 

 observed by us in the black seeded variety, that the oil content 

 would diminish at the same rate. Some slight correlation is 

 naturally to be expected, as the increase in one form of energy 

 supply is likely to be balanced by a decrease in the other form : 

 but the above relations point clearly to the fact that the 

 correlation is not by any means absolute. In addition to this 

 another test was made by bringing into consideration the 



