great spring rise, culminating in May, and followed after June
by a rapid descent to the minimum.

In Canada (see e.g., _Report of the Registrar General of the
Province of Ontario_ for 1904), the maximum and minimum of
conceptions alike fall later than in Europe; the months of
maximum conception are June, July, and August; of minimum
conception, January, February, and March. June is the favorite
month for marriage.

It would be of some interest to know the conception-curve for the
well-to-do classes, who are largely free from the industrial and
social influences which evidently, to a great extent, control the
conception-rate. It seems probable that the seasonal influence
would here be specially well shown. The only attempt I have made
in this direction is to examine a well-filled birthday-book. The
entries show a very high and equally maintained maximum of
conceptions throughout April, May and June, followed by a marked
minimum during the next three months, and an autumn rise very
strongly marked, in November. There is no December rise. As will
be seen, there is here a fairly exact resemblance to the yearly
ecbolic curve of people of the same class. The inquiry needs,
however, to be extended to a very much larger number of cases.

Mr. John Douglass Brown, of Philadelphia, has kindly prepared and
sent me, since the above was written, a series of curves showing
the, annual periodicity of births among the educated classes in
the State of Pennsylvania, using the statistics as to 4,066
births contained in the Biographical Catalogue of Matriculates of
the College of the University of Pennsylvania. Mr. Brown prepared
four curves: the first, covering the earliest period, 1757-1859;
the second, the period 1860-1876; the third, 1877-1893; while the
fourth presented the summated results for the whole period. (The
dates named are those of the entry to classes, and not of actual
occurrence of birth.) A very definite and well-marked curve is
shown, and the average number of births (not conceptions) per
day, for the whole period, is as follows:--

Jan. Feb. Mar. Apr. May June July Aug. Sept. Oct. Nov. Dec.
10.5 11.4 11 8.3 10.2 10.5 11.5 12.6 12.3 11.6 12 11.7

There is thus a well-marked minimum of conceptions (a depression
appearing here in each of the three periods, sep