80 Wager and Penis ton.—Cytological Observations on 
Meissner (’ 00 ) : Ueber das Auftreten und Verschwinden des Glycogens in der Hefezelle. Centralbl. 
f. Bakt. II, vi, pp. 517, 545. 
Merriman, Mabel L. (’ 06 ) : Nuclear Division in Zygnema. Bot. Gaz., xli, p. 43. 
Meyer, A. (’ 03 ) : Praktikum der botanischen Bakterienkunde. Jena, 1903, p. 80. 
- (’ 04 ): Orientirende Untersuchungen liber Verbreitung, Morphologie und Chemie des 
Volutins. Bot. Zeit., lxii, 113. 
Murphy (’ 99 ) : Some Aspects of the Pure Yeast Question. Jour. Inst, of Brewing, v, p. 432. 
Swellengrebel (’ 05 ) : Sur la division nucleaire de la levure pressee. Ann. de l’lnstitut Pasteur, 
xix, p. 503. 
Wager (’ 98 ) : The Nucleus of the Yeast-plant. Ann. Bot., xii, p. 449. 
- (’ 98 ): The Zygospore of Polyphagus Euglenae . Rep. Brit. Ass., lxviii, p. 1064. 
__ (’ 04 ): The Nucleolus and Nuclear Division in the Root-Apex of Phaseolus. Ann. Bot., 
xviii, 1904, p. 31. 
Will (’ 92 ): Die Hefenzelle, deren Aussehen und Beschaffenheit in den verschiedenen Stadien der 
Entwicklung und des Zerfallens unter dem Mikroskop. Allg. Brauer- u. Hopfenzeitung, 2. 
Festblatt, 1892, p. 1088. Ref. Errera (’ 05 ), 2. 
EXPLANATION OF FIGURES IN PLATES VI-X. 
Illustrating the Paper on Yeast by Mr. Harold Wager and Miss A. Peniston. 
Figs. 1-52 and 145-51 were drawn from one sample of yeast, obtained from the Albion 
Brewery. Figs. 101-12 are also from brewery yeast. 
Figs. 1-3, 8-15, 17, 18, 20-28 were made from living cells; Figs. 29-52 from fixed but 
unstained cells. 
Figs. 54-80, 94, 96-103, 105-8, no, 112-16 have been drawn from preparations stained with 
Heidenhain’s haematoxylin (mordaunting and subsequently reducing with ferric ammonium sulphate) ; 
Figs. 81-93 from preparations stained with haematoxylin after mordaunting in potash alum; Figs. 
163-8 and 170-2 from preparations stained with Mayer’s haemalum stain, and Figs. 173-82 from 
preparations stained with methylene blue. 
In all other cases special reference is made to the staining method. 
Except where otherwise stated, the drawings have been made from yeast fixed in Gram’s iodine 
solution. 
PLATE VI. 
Figs. 1-3. Yeast cells fresh from the brewery (24 hours’ fermentation). 
Fig. 4. The same yeast, after 5-10 minutes in Perenyi’s fluid, to bring out the nucleolus. 
Figs. 5-7. The same yeast, after running methylene blue under the cover-glass, showing the 
amount of volutin present. 
Figs. 8-15. The same yeast in Pasteur’s solution. Figs. 8 and 9, ten minutes in Pasteur’s 
solution; vacuole slightly contorted. Fig. 10, thirty minutes in Pasteur’s solution; vacuole sharply 
defined, turgid but somewhat smaller. Figs, n-13, one hour in Pasteur’s solution; vacuole 
very indistinct in 11 and 12 : in 13 it has apparently disappeared. Figs. 14 and 15, one and a half 
hours in Pasteur’s solution ; the cytoplasm is hyaline : the vacuole is invisible, but its presence is 
indicated by the position of the refractive granules. 
Fig. 16. The same yeast after the addition 01 Gram’s iodine solution ; the vacuole now shows 
clearly. 
Figs. 17 and 18. The same yeast, twenty-nine hours in Pasteur’s solution; vacuole again 
clearly visible and very large. 
Fig. 19. The same cell as Fig. 17, after the addition of iodine, showing position of nucleolus. 
