455 
relations. For the heart, lungs and liver of the newborn, two sets of 
measurements are quoted. The lungs in the first case were evidently 
in the unexpanded fetal condition. 
DoNALDSON also gives (upon the authority of F. P. MArr) the 
combined volume of brain and spinal cord in the human embryo of 
2 weeks at 0,04 cc., of 4 weeks at 0,2 cc., and of 12 weeks at 3,0 cc. 
Fig. 3. From a photograph of the right view of the model. On this side, the 
lower part of the body wall is not seen as on the left side, but has been dissected 
out to the mid-sagittal plane, giving a side view of the spinal cord, notochord, the 
descending aorta with its branches, and the pelvie viscera. 
Explanation (in addition to letters shown in Fig. 2): a’ right aortic arch. al 
allantois. 6 Wolffian duct. ca caudal artery. cl cloaca. D duodenum. ha hypogastric 
artery. i intestine. m notochord. o gall bladder. 7 rectum. ra right auricle. rv 
right ventricle. sp spinal cord. sv sinus venosus. w ureter. Its T-shaped upper ex- 
tremity, forming the anlage of the permanent kidney, is almost entirely hidden by the 
hypogastric artery. wp urinogenital papilla. vv vitelline (omphalomesenteric) vein. 
These figures for the embryos of 2 and 4 weeks are evidently too 
large, however, being apparently larger than the volumes of the entire 
embryos of those ages. 
It will be observed from the preceding table that the heart is 
relatively Jarge in the 11 mm embryo, being relatively about 6 times 
