REPRODUCTION IN LOWER PLANT LIFE. 1118) 
Society. We have an example more germane to our theme 
in the sterile flagellate cells which form the peripheral layer 
in Volvox. (See fig. 8, C.) These closely resemble ordin- 
ary zoospores in structure, except that the gelatinous 
membrane which envelopes each of them is pierced by a 
number of fine canals filled by extensions of the proto- - 
plasmic endochrome; these swarm-cells being therefore 
connected with one another and with the interior of the 
coenobe by an intricate network of protoplasmic threads. 
These flagellate cells are, in fact, the assimilating cells of 
the colony; they obtain the nutritive materials from the 
water, and pass it on through this protoplasmic network to 
the reproductive cells in the interior of the coenobe, and 
after having performed this function, wither up and die. 
It is by a careful study of the life-history of some of 
these lowest forms of vegetable life that the best oppor- 
tunity is afforded of learning something more than we know 
at present of the laws of adaptation by means of which— 
whether purely through natural selection, or through an 
inherent tendency to the transmission of adaptive peculi- 
arities —that extraordinary fertility of form has been 
developed which characterizes both the fauna and the 
flora of these latter days in the history of our globe. 
