DEVELOPMENT OF THE OPOSSUM DY} 
normal and 2 abnormal eggs of an early stage and after an 
interval of three days a perfect litter of 7 normal vesicles. 
Litter No. 339 from the left uterus is largely abnormal, whereas 
No. 339’ from the second operation was largely normal. Both 
batches of eggs from animal No. 294 were mostly abnormal, 
possibly on account of a temporary interference with the circu- 
lation of the uteri when the animal was twisted out of its lair 
TABLE 2 
Number of abnormal eggs at the bilaminar stage 
TOTAL NUMBER 
OF FERTILIZED 
EGGS 
NUMBER OF 
NORMAL EGGS 
NUMBER OF 
LITTER NUMBER ABNORMAL EGGS 
INTERVAL 
a. At first operation 
days 
339 0 1 5 6 
205 0 8 1 9 
343 0 9 2 11 
346 0 8 5 13 
353 0 11 0 11 
360 0 10 1 11 
Mortal east A 47 14 61 
23% 
b. At second operation 
299’ 4 6 3 9 
293’ 33 8 1 9 
339/ 1 6 1 a 
306’ 43 a 1 8 
191’ 3t 4 0 4 
Motallee ance 33 6 37 
10.8% 
after a method employed by hunters and applied in this case. 
Litters No. 175’ and No. 194’, twenty-five and twenty-eight days, 
respectively, after the removal of the left uterus, contained no 
abnormal eggs. 
Later embryos and foetuses present facts similar to those just 
indicated for the younger stages. To refer to special cases 
shown in table 4, No. 349, which had furnished only 3 normal 
