97 
REPRODUCTION among the LOWER FORMS of 
VEGETABLE LIFE. 
By Aurrep W. Bennett M.A., B.Sc., F.L.S., 
LECTURER ON BOTANY AT ST. THOMAS’S HOSPITAL, _ LONDON. 
With Plates II. and III. 
[Read 14th March, 1890.] 
In this paper which I have been honoured by being 
asked to lay before you, I propose to invite your attention 
to some phenomena connected with the modes of re- 
production which we meet with in some of the lower 
forms of vegetable life, especially the green forms belong- 
ing to the lower Algze and the Schizophycee. 
One of the most simple, and at the same time one of 
the most abundant, of these forms of life is the common 
Protococcus pluvialis, which occurs in two conditions, the 
motile and the resting state (fig. 1). I must ask your 
pardon for describing so familiar an objeci, but you will see 
my purpose presently. In the resting or palmella-condition 
each individual consists of a nearly spherical or somewhat 
polygonal cell, usually from 40 to 50 microns in diameter, 
with a thick cell-wall of cellulose. The change to the 
active state takes place by the protoplasm withdrawing 
itself from the cell-wall, and escaping in the form of an 
ovoid mass, provided with two very long and slender 
vibratile cilia or flagels, a pulsating vacuole, and a pig- 
ment-spot or “‘eye-spot.”” After being driven about rapidly 
for a considerable period with an apparently spontaneous 
motion, the motile protococcus comes to rest, loses its 
flagels, becomes encysted, and enters into its resting con- 
