1 8 4 



PROTOCOCCUS PLUVIALIS. 



PART II. 



The Protococcus pluvialis (fig. 7), one of the unicellu- 

 lar Confervse, is frequently met with in rain-water cis- 

 terns. The spore of the plant (fig. 7 A) is a globular pri- 

 mordial cell invested with a double coat of cellulose, 

 sometimes separated by an aqueous fluid, sometimes 

 not. The cell is filled with protoplasm, a colourless 



Fig. 7. Protococcns pluvialis : A, encysted cell ; B, c, cells divided into two ; D, cell 

 divided into four ; E, cell divided into eight ; F, cell divided into thirty -two ; G escaped 

 motile gonidia ; H L, primordial utricles furnished with cilia. 



watery liquid in which red and green particles are 

 scattered. When this spore begins to grow, the en- 

 dochrome, or solid matter in the primordial cell, divides 

 spontaneously into two similar and equal parts, round 

 at one end, and tapering to a point or beak at the 

 other, each being coated by a very thin film of the 

 transparent colourless protoplasm. 



After various changes, the green matter with several 

 red spots is condensed into the thick round half, while 



