456 
as large (in volume) as in the newborn, and more than 7 times as 
large as in the adult. 
The lungs, on the contrary, are relatively only ?/, as large in the 
embryo as the newborn lungs before expansion (volume 43,5 cc., or 
1,26 °/, of whole body), or !/, as large as the newborn lungs after 
expansion (volume 90 ce., or 2,62 °/)). The adult lungs, according to 
the figures given, appear to be of about the same relative size as the 
expanded lungs of the newborn. 
The liver in this embryo appears to be relatively only slightly 
larger than in the two newborn specimens for which figures are given, 
but it is relatively twice as large as in the adult. 
The brain in this embryo is seen to be relatively large. It is, 
however, not so large when compared with the newborn (about twice 
as large) as it is when compared with the adult (about 9 times as large). 
The spinal cord, however, shows the most surprising figures. That 
it is relatively enormous in size is evident from the portion visible in 
the model (Fig. 3 sp). Its volume, in this embryo, is exactly the same 
as that of the liver, or 4,85 %, of the whole body. This is about 
44 times as large, relatively, as in the newborn, and 115 times as 
large as in the adult! It is evident, moreover, when the figures for 
the brain and spinal cord are compared, that the brain falls off most 
rapidly in size (when compared with the entire body) between birth 
and adult life; whereas the spinal cord decreases most rapidly in re- 
lative size before birth. Comparing the newborn with the embryo, 
the whole body has increased about 35 000 times in volume, the brain 
about 19000 times, and the spinal cord about 830 times. From the 
newborn to the adult, the whole body increases about 17,4 times, the 
brain nearly 3,5 times and the spinal cord 6,4 times in volume. 
The head of the embryo is, as is well known, relatively very large, 
the trunk and extremities small. No exact figures for comparison 
with later stages are available, however. 
In form and relations, the various organs in this embryo agree, 
in general, with those of corresponding embryos already described in 
the literature. The more important relations are shown in the two 
views (Figs. 2 and 3) of Mr. Bonnot’s model. A brief description of 
the various structures is given under the explanation of these figures. 
The levels of the principal organs with respect to the vertebral 
column were observed, and are indicated in the following table. The 
levels at this stage are most readily determined by means of the 
corresponding spinal nerve roots. All the organs noted lie at levels 
considerably higher than in later stages. 
