788 
in pairs, which obstruct the tides and create de- 
posits in the pathway of commerce, thus increasing 
the cost. 
On Thursday evening a celebration of the cen- 
tenary of the introduction of gas as an illuminant, 
under the auspices of the American Philosophical 
Society, the Franklin Institute, the American 
Chemical Society and the American Gas Institute, 
was held in the hall of the Franklin Institute, 
Philadelphia, with President Keen in the chair. 
A paper on ‘‘ By-products in Gas Manufacture,’’ 
_ by Charles E. Munroe, was read. 
Fripay, AprRin 19—Mornine SESSION 
President Keen in the chair 
Heredity of Feeble-mindedness: Henry H. Goo- 
DARD. Introduced by Dr. Henry H. Donaldson. 
The Inheritable Factors of Epilepsy: Davi F. 
WEEKS. Introduced by Dr. Henry H. Donald- 
son. 
Is the Control of Embryonic Development a Prac- 
tical Problem? CHARLES R. SrocKarD. Intro- 
duced by Dr. Henry H. Donaldson. 
Many deformities occur among animals in na- 
ture and a great number of deformed human 
beings are born. Many other individuals suffer 
from minor defects in bodily structure. These 
defects are often internal and may be unknown 
to their possessor, yet they frequently give rise to 
disease conditions which sometimes actually result 
in death. There are, for example, many congenital 
defects of the heart and other parts of the circula- 
tory system, digestive tract, reproductive organs 
and developmental arrests may occur in almost all 
parts of the body. 
These conditions must be regarded as a struc- 
tural disease which causes the death of a number 
of children before they are born and handicaps 
many others throughout their lives. The cause of 
such defects must be ascertained, then a possible 
means of control may be found. 
Observations on human families and experiments 
on lower animals prove that these conditions are 
due to one of two causes as the case may be. 
First, the embryo may have developed in an un- 
favorable chemical environment; or secondly, the 
germ cells of one or both parents may have been 
defective. 
When the eggs of lower animals are treated with 
various poisons during their development they give 
rise to monstrous individuals. For example, when 
developing fish’s eggs are treated for a short time 
with alcohol in some cases as many as 98 in 100 
SCIENCE 
[N.S. Vou. XXXV. No. 907 
of the eggs give rise to fish which show almost all 
known deformities of the brain, eyes and other 
parts of the nervous system. 
Guinea-pigs have been put into a state of chronic 
alcoholism and when such animals are mated either 
together or with normal individuals the resulting 
offspring are greatly affected. Many are aborted 
early in development, or reach term and are then 
born dead. Only a few are born alive and the 
great majority of these die after a short time, 
showing many nervous disorders and dying in 
convulsions. 
A normal female when mated with an alcoholic 
male gives an almost equally poor result. This 
shows that the paternal germ cells are affected 
by the alcohol and are thus rendered unable to 
give a normal combination and abnormal offspring 
are produced. 
Abnormal and deformed individuals may thus 
be artificially produced at will and the provoking 
cause is proved to be an unfavorable chemical 
environment acting on the germ cells of the parent 
or directly upon the embryo. The proposition of 
reversing the experiments thus presents itself, and 
some mode of treatment ‘or control should be de- 
vised by which parents may be put into the proper 
state to produce as nearly as possible a normally 
vigorous offspring. Enough is known at present 
to make the control of development possible to a 
slight degree at least. 
An Avian Tumor in tts Relation to the Tumor 
Problem: PrEyToN Rous. Introduced by Dr. 
Alexander C. Abbott. 
The paper reports the results of an experimental 
investigation into the cause of a malignant tumor. 
For the work a sarcoma of the chicken has been 
employed. This growth is transplantable from 
fowl to fowl, and presents the typical picture of 
a malignant tumor. It has been studied under 
many different conditions, not only in the adult 
fowl, but, by a special technic, in the chick pre- 
vious to hatching. 
Attempts to isolate a cause for the sarcoma 
have been successful. By filtration, or by drying, 
there can be separated from the living tumor 
tissue an agent which will produce the growth in 
fowls previously healthy. This active agent has 
not been directly observed, and is in all probability 
ultramicroscopic, since it will pass through filters 
which hold back minute bacteria. Its properties 
identify it as a living organism. In giving rise to 
a tumor it seems able to act only exceptionally 
and at points and upon tissues which have been 
