1912] Long: Living Eggs of Rats and Mice 119 
objective 
supply bottle 
waste bottle 
Fig. K. Cireulation slide in position on stage of microscope under an 
objeetive and connected with supply and waste bottles. The supply 
bottle is covered by a perforated glass cap; it is supported on a cireular 
dise shown in plates 16 and 17. & W%. 
escape only through the narrow space above the shelf (sh.), 
which is shown in the enlarged sectional view of the outlet end 
of the cell (fig. L.), while objects of large enough size are retained 
in the cell. Thus mammalian eges are held back by coming into 
aL: nee 
TK MM ANAT ANI ANN 
Cc 
sh./ Tr 
Fig. L. Semi-diagrammatie longitudinal section through part of the 
upper slide (up. sl.) at the outlet end of the cell; i.e., through part of 
the cell, the shelf (sh.), the depression (dep.) and hole (c) shown in the 
figures I and J. Cover- glass (cov. gl.) above. X 25. It shows two eggs 
and the way in which one is being prevented from being washed away by 
the current which passes from right to left. 
