SECT. ii. PROTOCOCCUS PL UVIALIS. 185 



the tapering beaked part is left transparent, being only 

 filled with, the watery liquid. Both bodies are then 

 coated with cellulose, and two vibratile filaments called 

 cilia, from their resemblance to eye-lashes, proceed from 

 a point near the beak. The whole of these changes 

 take place while the two bodies are still within the 

 common cellulose covering ; the moment they come out 

 of it, by a rupture in the cell-wall, they swim about 

 with the greatest velocity by means of their cilia, which 

 lash the water so rapidly 'that they are invisible even 

 with a microscope. The activity of these zoospores, as 

 they are called, continues for about an hour and a half ; 

 the motion then becomes gradually less rapid ; the cilia 

 may now be seen, and soon fall off; then the bodies ac- 

 quire a firmer coat of cellulose, and sink to the bottom of 

 the water, where they remain at rest as still, or winter 

 spores. There is great variety in the Protococcus, for the 

 matter in the primordial cell sometimes divides not only 

 into two equal and similar parts, but into 4, 8, 16, 32 

 equal and similar parts consecutively ; each brood is de- 

 veloped into zoospores, which ultimately become resting 

 spores. 



When a spore is to be formed in a primordial cell, 

 the starch and green matter condense into a nucleus in 

 its centre, and a membrane envelopes the liquid and the 

 nucleus within it, so that a spore in its first stage is a 

 free and independent cell containing azotized matter 

 swimming in a formative liquid. If the spore is to be 

 motile it remains of a green colour, and gets cilia ; but 

 if it is to be a winter spore, the internal matter forms 

 into granules, mixed with particles of red oil, which 

 coalesce into a drop, and it generally undergoes the 

 same transformations as those which take place after 

 the conjugation or union of two adjacent cells into one 

 as already described. The zoospores may lose their 

 cilia, fall to the bottom of the water as green spores, and 



