74 American Statistical Association. 



of the plienomenon with the period of puberty which presents 

 a similar difference in the time of its occurrence. On the 

 principle, clearly enunciated by Carpenter * and by Herbert 

 Spencer,! that growth and reproduction are to some extent 

 antagonistic processes, it may perhaps be reasonably supposed 

 that at the age at which the organism becomes potentially 

 reproductive will not be a period of excessive growth, and 

 an examination of the data at our disposal seems to show 

 that this is the case. It is of course almost impossible to 

 determine statistically the average age at which males become 

 capable of reproduction ; but for the female sex the first 

 appearance of the catamenia furnishes a satisfactory indica- 

 tion that this period has been reached. Few data have been 

 collected for determining the age at which American women 

 begin to mensurate, but Dr. J. R. Chadwick has kindly per- 

 mitted the use of his manuscript tables containing the records 

 of observations on patients at the Boston Dispensary and the 

 Boston City Hospital. From these records observations on 

 575 American-born women have been selected and arranged 

 in the following table in such a way as to indicate whether 

 the date of the first menstruation was given approximately 

 or accurately : — 



* " There is a certain degree of antagonism between the nutritive and reproductive 

 functions, the one being executed at the expense of the other. The reproductive apparatus 

 derives the materials of its operations through the nutritive system, and is entirely depend- 

 ent upon it for the continuance of its function. If, therefore, it be in a state of excessive 

 activity it will necessarily draw off from the individual fabric some portion of the aliment 

 destined for its maintenance. It may be universally observed that, when the nutritive 

 functions are particularly active in supporting the individual, the reproductive system is 

 in a corresponding degree undeveloped, and vice versa." — Principles of Physiology, 

 General and Comparative. Third edition, 1851, p. 5i)2. 



t The Principles of Biology. Vol. II, chap. 6. 



