PLATE 1. 



THE YEAST PLANT. 



FIG. 1. Showing 



i Cell-wall or sac. 

 A CELL J Protoplasm (Gr. protos, first; plasma, from plasso, to mould). 



( Vacuole filled with cell-sap (L. vacuum, an empty space). 

 Fios. 2, 3, and 4. Showing 



MULTIPLICATION BY BUDDING OB GEMMATION (L. gemma, a trad). 



The commencement of the process is seen in fig. 2. A bit of protoplasm is pushed out, 

 stretching the cell-wall and making it thin. Fig. 4 shows a cell aggregate or colony produced 

 by a repetition of the process of budding. 

 FIG. 5. Showing 



MULTIPLICATION IJY ENDOGENOUS DIVISION (Gr. etulon, within; gennao, I produce). 



The protoplasm collects usually into four round masses, each of which takes on a cell-wall. 

 Cells produced in that way are called Ascospores (Gr. askos, a bag; sjnra, a seed) or Endo- 

 conidia (Gr. endon, within; konis, dust). 

 Fia. G. Showing 



AS'COSPORES set free by rupture of the cell-wall of parent, and multiplying by gemmation. 

 Fio. 7. Effect of 



Magenta Stains protoplasm, leaving cell-wall comparatively unstained. 



Crushing Kuptures the cell-wall, and shows that the cell-wall is tough and resisting, while the 



protoplasm is semi-fluid. 



Potash (KHO) Dissolves out the protoplasm. 

 Iodine Stains protoplasm. 

 FIG. 8. Measurement by eyepiece micrometer. 



DIAGRAM I. PHYSIOLOGY 



a. Shows the composition of a fluid fit to nourish yeast (Pasteur's fluid). 



Elements which make cell-wall (C.O.H.). 

 Elements which make protoplasm (C.O.H.N.). 

 Elements which make ash (P.S.K.Mg.Ca.). 



b. Shows the composition of the fluid when acted upon by yeast. Process of fermentation 



(ferveo, I boil). 



I Carbonic acid (CO.,). 

 Sugar becomes < Alcohol. 



( Small quantities of succinic acid and glycerine. 

 About two per cent, of sugar is unaccounted for. 

 Ammonium tartrate, etc., used up by the yeast. 



Total result -f ^ anu ^ ac '' ure f alcohol and carbonic acid. 

 1 Manufacture of cell-wall and protoplasm. 



CLASSIFICATION OF YEAST. 



Kingdom Plantae, because it possesses a cell-wall made of cellulose, and can manufacture 



protoplasm. 

 BubJ&ngdem Thallophyta, because it possesses neither root, stem, nor leaf. 



s Protophyta, because it has no sexual process of multiplication (Gr. prntna, first; ptnjton, 

 plant). 



A 



