740 
game title on page 676, where on the other 
hand the main word of the title is omitted. 
The Beitrige of von Staudt appeared in two 
parts, the first in 1856, the second in 1860. 
How could Whitehead have made the mistake 
of calling this second part a “ 3rd ed.” ? 
GxrorcGE Bruce Hatstep 
GREELEY, COLO. 
PEARL AND JENNINGS ON ASSORTATIVE CONJUGA- 
TION IN THE PROTOZOA 
In general, the scientist’s investigations re- 
ceive the recognition they deserve from his 
fellow workers. This is true because the bulk 
of research consists in the working out of 
details in a scheme already stamped with au- 
thority. It is the unexpected, fundamentally 
new or truly brilliant result upon which the 
doctors disagree. 
One of the best illustrations is a paper in 
Biometrika for February, 1907. In the dem- 
onstration of the existence of an assortative 
conjugation or homogamy in Parameciwm 
analogous to the assortative mating previously 
found by Pearson in man, Pearl seemed to 
some of us to have struck a rich vein hitherto 
passed over by all prospectors. Others 
thought differently. Pearl’s assays were dis- 
credited. In America, at least one review was 
declined. In England, J. J. Lister illustrated" 
by Pearl’s paper his warning to biometricians 
to be sure they have a problem which is 
“ sound from the standpoint of biology before 
bringing a formidable mathematical apparatus 
into action for its investigation.” 
Open criticism like that of Lister was more 
easily met? than the general indifference 
largely attributable to the odiwm mathema- 
ticum. This is now in a fair way to be over- 
come by the results being announced by Jen- 
nings. If these, in their turn, are being re- 
ceived by zoologists with but lukewarm en- 
thusiasm, the fact indicates merely that the 
work is in advance of its time. 
His recent study of conjugation in Para- 
1Lister, J. J., Nature, Vol. 74, pp. 584-585. 
2Pearson, K., Nature, Vol. 74, pp. 465-466, 
608-610, 635, 1907. 
3 Jennings, H. S., ‘‘Assortative Mating, Varia- 
bility and Inheritance of Size in the Conjugation 
SCIENCE 
[N. 8. Vou. XXXV. No. 906 
mecium® must be considered in comparison 
with Pearl’s pioneer paper.* 
a. Differentiation of Conjugants in Type 
and Variability—The general belief that con- 
jugants are on the average smaller than non- 
conjugants is quantitatively substantiated. 
In eleven “pure lines” Jennings found con- 
jugants to be from about 4 to nearly 14 per 
cent. smaller than the non-conjugants. In 
“wild” cultures, or in a mixture of differen- 
tiated pure lines, the mean for conjugants 
may be higher because only the large pure 
line is in conjugation. On the other hand, 
the conjugants may be abnormally small, 30 
per cent. less than the non-conjugants, be- 
cause only the smaller of the lines in the mix- 
ture is in conjugation. 
Both absolutely and relatively, the conju- 
gants are less variable than the non-conju- 
gants. The difference in variability may be 
slight but generally it is large, for the con- 
jJugants are on an average about 33 per cent. 
less variable (relatively) than the non-conju- 
gants. 
The possible causes of this reduced varia- 
bility are discussed. Lister’s “Gametic Dif- 
ferentiation” is dismissed. Pearl’s conclu- 
sion that equalization of individuals (undif- 
ferentiated or proconjugants) during the 
process of conjugation can not account for 
the lessened variability is confirmed. Jen- 
nings’s conclusion, supported by abundant 
evidence, is that the low variability of con- 
jugants is fully accounted for by the fact that 
conjugation does not occur till a certain 
growth stage has been reached, and does not 
occur in the largest individuals—the measur- 
able variability of Paramecium being largely 
a growth phenomenon. Thus, the conjugants 
represent a definite and rather limited growth 
stage, the exclusion of both the larger and 
of Paramecwum,’’ Journ, Exp. Zool., Vol. 11, pp. 
1-134, July, 1911. 
‘Pearl, R., ‘‘A Biometrical Study of Conjuga- 
tion in Paramecium,’’ Biometrika, Vol. 5, pp. 213— 
297, 1907. 
5The offspring of a single individual repro- 
ducing by fission has been called by Jennings a 
‘pure line.’? In retaining the term here nothing 
more is implied than guaranteed purity of descent. 
