PROGRESS IN BIOLOGICAL INQUIRIES, 1926 663 
computations of length, based on the diameters of scales, are more accurate 
than those based on the anterior radius, the dimension now universally 
employed. All my computed data on the growth of the coregonines are based, 
therefore, on diameter measurements. Second, the so-called ‘ Lee’s phenomenon 
of apparent change in growth rate,’ a characteristic of the computations of 
length of virtually all species of fish for which calculations have been made, is 
due to perfectly natural events in the life history of the lake herring, and no 
corrections for it should be made. Briefly, Lee “phenomenon” is this: When 
we compare the calculated lengths derived from the scales of the various age 
groups of a collection, or of a year class, with one another, we find that for 
corresponding years the lengths computed from the scales of old fish are, nearly 
always, lower than those calculated from the scales of young fish; that is, the 
amount of calculated growth at corresponding ages increases regularly as the 
scales used are taken. from fish of younger age groups. Thus, if the first 
year’s growth inerement is calculated from the scales of a 6-year fish, it is 
less than if calculated from scales of a younger fish. ‘This is true, even though 
the fish belong to the same year class, that is, hatched in the same year and 
grown up under the same environmental conditions. 
It is now generally believed that Lee’s “ phenomenon” is caused by the fact 
that scales do not begin their development until the fish has grown to a cer- 
tain length. The growth history of the early part of the first year of life is 
not registered on the scales, therefore. This, if ignored, presumably intro- 
duces an error into the computations of length, which are based on the as- 
sumption that the entire history of the growth of the body of a fish is reg- 
istered faithfully in its scales. On the basis of this belief, certain investi- 
gators apply a corrective formula to their computations of length. 
My herring data, however, show that this corrective formula does not 
eliminate the ‘‘ phenomenon,” although it does become less pronounced; and 
that the length values, after having been corrected by this formula, appear 
to be too high for the eariy years of life. Further, the discussion shows that 
the corrective formula does not take into consideration the rapid growth of 
the scale, as compared with that of the body, especially the rapid growth 
occurring immediately after the scale appears during the first year of life. 
The effect of this relatively rapid scale growth upon the calculated lengths. 
is exactly the opposite of that produced by the late appearance of the scale, 
and the former neutralizes or counterbalances (at least, in part) the latter. 
Finally, the data show that the “phenomenon” not only characterizes the 
computed lengths but also the direct measurement of the scale diameters. 
That is, if we measure the annular diameters (the diameters included in the 
annuli) of the scales of the several age groups, of a year class, or of a sample, 
we find that for corresponding years these diameters in the scales of the old 
fish average less in length than those in the scales of the young fish—cor- 
responding diameters decrease progressively with age. Obviously, tardy scale 
formation can not be a factor of the “phenomenon” found in the direct 
measurements of scale diameters, inasmuch as in them no computations are 
involved. 
I may state, incidentally, that in the lake herring, Lee’s ‘“ phenomenon” 
may be explained best as the result of four natural events in the life history. 
They are, briefly, as follows: 1. The late-maturing fish of a year class are 
the more slowly growing individuals of their year class. 2. The scale grows 
relatively faster than the body. 38. Sexual maturation retards the rate of 
growth. 4. A compensation in growth occurs—that is, fish that grow slowly 
during the earliest years of life grow rapidly during the later years of life, 
und vice versa. Lee’s ‘ phenomenon” is a natural event—it should be pres- 
ent in the herring calculations of length and no correction should be made 
for it. 
In general, I found that the assumptions underlying the scale method were 
valid in the lake herring, and that the method may, therefore, be applied 
with confidence in a study of the life history of this species. The natural 
history of the lake herring is, briefly, as follows: 
Lake herring may be taken at almost every port on Lake Huron. Saginaw 
Bay ranks first in the herring industry of this lake, while Alpena ranks second. 
Herring are taken in either pound or gill nets (in trap nets rarely) in the 
fall and spring of the year (the big catches are made in the fall during the 
spawning run). After June, most adult herring have moved out of the 
shallow water. 
The herring occasionally take their food from the bottom, though they 
are typical pelagic feeders, subsisting principally on the plankton forms. 
