608 
GENETICS: R. J. STOCKING 
of individual susceptibility to alcohol. Theoretically it seems to follow 
that the effect on the motor coordinations indicates a central tendency 
of alcohol. 
A full presentation and discussion of the various techniques and the 
resulting measurements are given in PubHcation No. 232 of the Carnegie 
Institution of Washington. 
^Tentative plan for a proposed investigation into the physiological action of ethyl 
alcohol in man. Privately printed and distributed January 1, 1913. 
VARIATION AND INHERITANCE IN ABNORMALITIES 
OCCURRING AFTER CONJUGATION IN 
PARAMECIUM CAUDATUM 
By Ruth J. Stocking 
ZOOLOGICAL LABORATORY. JOHNS HOPKINS UNIVERSITY 
Presented to the Academy, November 4, 1915 
In view of the difficulty of interpreting from the standpoint of evo- 
lution the changes that occur in the complex phenomena of inheritance 
from two parents, the study of reproduction from a single parent becomes 
of great importance. One of the difficulties in such work is that the 
lower organisms, in which uniparental reproduction commonly occurs, 
present relatively few characteristics that are at the same time variable 
and hereditary, among closely related individuals; though this is a condi- 
tion demanded for studies of heredity and evolution. 
Certain abnormaHties that appear after conjugation in the infusorian 
Paramecium appeared to offer a favorable opportunity in this respect. 
These abnormalities vary greatly in occurrence, character, and degree; 
at the same time they are partially heritable. This paper is a summary 
of an extended study of these abnormalities in relation to the problems 
of inheritance, variation, and racial change. 
Among the progeny of a large proportion (from 36 to 81% in differ- 
ent experiments) of exconjugants of Paramecium caudatum, abnor- 
malities appear frequently. These abnormalities consist of irregularities 
in body form and dimensions, of many diverse types. Among them are 
monsters due to partial or irregular fusion; single bodies some larger, 
some smaller than normal; and a great variety of abnormal shapes. 
These animals propagate by fission; some of the lines of individuals 
thus derived from the exconjugants are quite without abnormalities, 
in others under the same conditions the abnormalities reappear for 
generations. Thus the abnormaUties are hereditary. But diversities 
appear also within the abnormal lines themselves. Some of the indi- 
