488 
In regard to frog’s eggs, O. Herrwie 5° found that after four days inter- 
ruption at 0° C. the eggs showed at first a normal development and then 
exhibited permanent injury. O. ScHULTzE ®! in his studies of Rana fusca noted 
that the eggs could stand a 14 day complete checking of development and 
then go to gastrulation without any visible disturbances. 
Among other methods for inducing malformations in chicks (besides 
interruption of development) are the following: 
1. Rotation or shaking as carried on by LomBarpini at Pisa °? in 1868 and 
by Marcoccı5® and DARrESTE. 
2. Conduction of electric and electro-magnetic currents by LoMBARDINI, 
MARGIORUM 5* and WINDLE®?, 
3. Use of very low and very high incubation temperature by DARESTE, 
RıcHTER,5® KoLuMmann ®”. 
4. Direct interference by LEUCKART, SCHRoHE °® (Giessen 1862), VALENTINE, 
SCHYMKIEWICZ,5°° Fou and WARYNISKI. 
Horrmann * describes a specimen of anadidymna in a chick embryo. 
An interesting malformation noted in avian embryos has been described 
by Dareste, For, Waryniski, Rapaup ° and KAESTNER as omphalocephalia. 
In this condition the heart forms the cephalic extremity of the embryo, 
then is seen the neck, while the head is found near the yolk-sack caudad 
to the heart. The experimental production of the malformation was carried 
out on duck’s and hen’s eggs. If the embryos are healthy they will live 
from 2 to 6 days. The malformation does not seem to occur in the early 
stages of development as Four and Warynıskı have shown that pressure upon 
the exposed embryonic areas in the middle of second day of incubation in 
chick and at the beginning of the third day in ducks produces the disturbances. 
When the embryo consists of 15 to 17 somites the heart through the yield- 
ing of its flexure has become noticeably asymmetric on its right side and 
begins to pulsate while the head is still symmetric or just beginning to turn 
on its left side. The head is sharply demarkated caused by the head fold of 
the amnion which may be readily followed to a region where the omphalo- 
mesenteric veins empty into the heart. The otic depressions are well formed. 
Following this the head in the region of the mid-brain begins to bend ven- 
trally, pushing the cardiac ventricle before it so that the caudal extremity 
of the ventricle sinks deeper (toward the yolk-sack). As a result the front 
of the head is gradually drawn dorsally so that the frontal portion does not 
project beyond the heart while the cervical extremity of the head lies in the 
neighborhood of the third or fourth somite. This change continues until the 
head bend becomes so sharp that the dorsally (and caudally) drawn head 
reaches the ventricle, glides completely into the “ Herzschenkel” and disappears 
toward the yolk-sack dorsal to the heart in order to gradually bend back- 
ward, in toto, upon the yolk-sack. Into the depression dorsal of the heart 
the head, vessels, notochord and amniotic fold disappear. Only a slight ento- 
dermal groove that is deeper laterally than medially represents the foregut 
in this region; apparently retrogression thereof had occurred. The heart did 
not seem abnormally large, although it may have been hypertrophied. 

j" u f oe= 
