1 8 . YEAST PARTICLES 



with the greatest certainty, as represented in Fig. 8, 

 plate I. 



The material of which the cell wall consists (formed 

 material) passes gradually into the germinal matter, 

 when the plant is germinating quickly, and the abrupt 

 line, which marks the internal boundary of the cap- 

 sule in many specimens, is absent. These points are 

 given in the drawings, Figs. 7 and 8, the latter, in which 

 the formed material is made too thick, taken from a 

 specimen magnified by the fiftieth. 



Where growth is active, the yeast cells are em- 

 bedded in a soft material continuous with the external 

 surface of the envelope, as represented around the 

 yeast particles in the central part of Fig. 8. This 

 probably consists partly of matter which is drawn 

 towards the surface of the cells by the currents of 

 fluid which are setting towards the germinal matter 

 within, and partly of imperfectly hardened formed 

 material. Thus there always appears to be a space 

 between the outer part of one and the outer parts 

 of neighbouring cells, 



The very soft material, which consists of imperfectly 

 formed matter, that by gradual condensation as- 

 sumes all the characters of the cellulose wall of the 

 yeast particle, corresponds to the mucus which lies 

 between the particles of bioplasm concerned in the for- 

 mation of that substance, and bears the same relation 

 to the envelope of the yeast cell as the viscid mucus 

 does to the wall of an epithelial cell embedded in it. 



