n.] PROTOCOCCUS. 15 



b. Cells multiplying by fission : 



a. Simple fission. The cell elongates, and the 

 protoplasm divides into two across its longer 

 axis, and then a partition is formed sub- 

 dividing the sac; the halves either separate 

 at once, and each rounds itself off and be- 

 comes an independent cell ; or one or both 

 halves again divide, in a similar way, before 

 they separate, and so three or four new cells 

 are produced. 

 /?. Cells multiplying by budding, like Torula; rare. 



b. Motile stage. 



a. Mount a drop of water containing motile Proto- 



coccus, and examine with a high power. Note 

 the actively locomotive green bodies, of which 

 two varieties can be distinguished. 

 a. Cells like the stationary ones in size, and 

 apparently directly formed from them. Each 

 possesses a structureless colourless sac, sur- 

 rounding the coloured protoplasm, but the 

 latter has shrunk away from the sac at most 

 points. 



Note in various specimens The two cilia 

 prolonged from the protoplasm through aper- 

 tures in the sac ; their motionless part within 

 the sac ; their vibratile portion outside it. 

 The colourless thin external layer of the 

 protoplasm collected into a little heap at the 

 point from whence the cilia arise. The deli- 

 cate colourless processes radiating from the 

 outer protoplasmic layer to the interior of the 

 sac. The colour usually green, but frequently 

 one bright red spot is present. 



