712 



THE AMERICAN NATURALIST 



[Vol. XLIX 



In Hibiscus the differentiation of the individuals with respect 

 to number of bracts seems to be greater than that for number of 

 sepals. For both Staphylea and Hibiscus the correlation for 

 ovules is generally high. It is in every instance higher than 

 that for mean number of seeds matured per fruit. Correlation 

 for both mean number" of seeds per fruit and relative number 

 of seeds matured has a moderately large value in Hibiscus, but 

 in Staphylea it is sensibly 0. In both species such character- 

 istics of the ovary as radial asymmetry and locular composition 

 seem to be rather sharply differentiated from individual to indi- 

 vidual. This is probably due in part to differentiation with 

 respect of number of ovules per fruit, but further discussion of 

 the problem would be out of place in a note, the only purpose 

 of which is to call attention to the usefulness, in both applied 

 and pure science, of a quantitative means of detecting and ex- 

 pressing permanent differentiation. 



In this brief review I have made no attempt to discuss fully 

 all the biological phases of the problems suggested. The analysis 

 of the data may in several instances be carried much further by 

 the use of the statistical tools. Perhaps enough has been said to 

 indicate that inter-annual coefficients may be of real service in 

 practical animal husbandry, in plant breeding and in mor- 

 phology and physiology. More than usefulness is not to be ex- 

 pected of any method. 



J. Arthur Harris 



THE PHENOMENON OF SELF STERILITY 



In my paper which appeared in The American Naturalist, 

 Vol. XLIX, p. 79, the last seven lines on page seventy-nine 

 should read as follows: 



