30 MALL. [Vor. XIX. 
are arrested and strikingly abnormal. These embryos grow in 
an irregular fashion, become cedematous and the lymph vessels, 
blood-vessels and serous cavities are distended. Especially is 
the pronephros thus affected and the glomerulus distorted. 
The vascular system is much distended and very irregular, the 
chief vessels being laid down, though incomplete. The aorta 
and pronephric sinuses open into a mesenteric sac. The capil- 
lary system is imperfect or absent, blood corpuscles are rela- 
tively few and apt to be collected in the enlarged sinuses. Re- 
markable also is the role the lymph hearts play in such speci- 
mens. They continue to beat and pump the lymph containing 
some blood into the veins, and from their periphery it must 
pass again into the tissues. In connection with arrest in the de- 
velopment of organs the coiling of the intestines is limited to a 
single loop, the pancreas and liver are not normal, the sub- 
divisions of the brain do not acquire their specific size and 
shape, the eyes are much aborted and the musculature is vacu- 
olated. Knower obtained similar results from frog embryos 
developed in acetone chloroform, which inhibits the heart 
action from its earliest stages. 
The recent experiment of Bardeen, in which he produced 
toad monsters by subjecting the sperm to the influence cf 
X-rays before fertilization, may also bear upon the question 
of the importance of the heart in early development. “The 
eggs develop at first apparently normally or even better than 
the control, but beyond the gastrula stage the development 
begins to become retarded, and at the time of hatching, as 
the tail begins to grow out, marked deformities begin to 
appear in the larve.” The change takes place at the time 
the heart begins to function, for the vascular system was 
barely developed in any of the embryos experimented upon. 
The heart is rudimentary and may have no continuous lumen. 
The chief arteries and veins are incompletely developed. 
There are but few blood corpuscles in any of the embryos, 
and Bardeen® states that it is uncertain whether the blood had 
“Bardeen, Jour. Ex, Zool., Baltimore, 1907. 
