136 HALSEY J. BAGG 
EXPERIMENTAL RESULTS 
Series A. Injections of radio-active solutions 
I. Subcutaneous injections after mating. Sixty-five full-grown, 
normal, pregnant rats were treated in this series. They were 
divided into four groups, each treated at different periods after 
mating. ‘Ten pregnant females were injected 7 days after mating; 
twenty-four, 10 to 14 days after; twenty-one, 15 to 17 days after; 
and ten, 18 to 21 days after mating. Many of the animals were 
killed at weekly intervals after treatment, although some were 
allowed to reach full term. 
Various degrees of developmental disturbances were noted, as 
shown in the following groups: 
1. There was a large number of cases where no embryos 
developed, in others many began development, but were absorbed 
or aborted at an early time. The females in which no embryos 
were found, although they were definitely considered pregnant 
before treatment, occurred among cases treated soon after mating 
and in those instances where females were autopsied a consider- 
able time after treatment. Figure 1 shows the remnants of 
maternal and embryonic structures; from the size of the placentae 
one can see that the foetuses had reached a fair degree of develop- 
ment before the radiation retarded the normal physiological 
processes. In one case (fig. 2) a small ovoid sac was found 
attached to the uterine wall by a thin stalk. This apparently 
represented the remnants of a former embryo and placenta. 
Extravasated blood and cell detritus were found in this sae and 
a great many large cells of an epithelioid nature that probably 
belonged to the former embryonic syncytium. The wall of this 
cyst was formed by fibrous connective tissue. 
2. Embryos were killed by the treatment, but were removed 
from the mother and preserved before they were absorbed. 
These showed various extravasations from the vessels of the 
subcutaneous connective tissue, within the meningeal sinuses, and 
mainly along the dorsal midline of the body. Figure 3 shows a 
typical example of such a lesion which was situated in the mid- 
dorsal line. The mother of this embryo, no. 1167, was mated on 
