W. Bernard Crow. 
* 5 ^ 
represented by a polygonal hood opening to the interior of the 
sphere and covering each protoplast, adjacent hoods fitting 
together and having soft flhrids running from their corners to the 
middle of the colony where a complete inner lamella of the sphere, 
corresponding to the aggregated inner parts of the lamella in 
V. globatov is formed. 
Fio. 2. Diagram to show membrane structure in (A) Sblusvella dvoebakensis, 
(B) Stephanosphceva pluvialis, (C) Volvox tcvtius , (D) V. globatov, (E) V. aureus. 
C, D and E are portions of the outside of the colony in vertical section : 
a, outer layer of membrane; b, inner layer 5 c , intercellular mucilage. 
Protoplasts black. 
Still more important than the lamella are the pit-canals in 
the cell-walls of Volvox. They are quite like those of the higher 
plants and contain strings of ordinary cytoplasm connecting 
adjacent cells. In V. globator they are comparatively wide 
structures which break up into finer threads in passing through 
