160 LABOHATOBY STUDIES OF CRYFTOQAMS 



362 (Compound). Bacteria. — With a needle transfer to a slide a 

 bit of the scum that gathers on water in which vegetable matter is 

 decaying. Cover with a cover glass and examine with a high power. 

 Tlie Bacteria are glistening white (i.e. colorless) bodies of small size 

 often occurring in broad patches of gelatinous matter (the matter 

 which holds the "scum" together) in which they are more or less 

 evenly spaced ; or occurring in chains or threads. Some may be spiral 

 in form and exliibit very active motion. Having found the Bacteria, 

 remove the cover glass, spread the scum out thin on the slide, and 

 dry this preparation by holding it at some distance above a flame. 

 Wlieu the last bits of the spread scum are about to become dry, 

 remove from the heat and add drops of geutiaii violet stain.' After 

 a moment wash this off with a little water, cover, and reexamine. 

 The various forms, now more plainly seen, are to be drawn. 



For suggestions as to the biological study of Bacteria see Appendix. 



363 (Compound). Yeast. — Mount in water a snudl bit of yeast 

 cake, spreading the material out thin, and examine witli a high power. 

 Are the yeast plants of uniform size? Have they any peculiarity of 

 form, common to all, or nearly all (i.e. are they uniformly spherical, 

 or elliptical, or ovate, etc.)'.' Have they any common features of 

 internal structure? Having determined these points in your owu 

 mind, make a drawing of a typical yeast plant of the species you have, 

 the drawing to be large enough to show easily any internal features.- 



364 (Compound). From mateiial that has been growing for a few 

 hours in sweetened water (a teaspoonful of sugar to a half glass of 

 water), study the method of multiplication. Do the buds — the new 

 individuals growing out from the bodies of the old plants — spring 

 from any particular region, as a rule? Draw in outline three stages 

 in the budding process. 



365. Is any action of the yeast upon or in the sugar solution 

 to be seen? To test this, drop small pieces of yeast cake into tum- 

 blers of (1) sugar solution, (2) water alone. In fifteen minutes or 

 so the residt should be observable, and within an hour very mai'ked. 

 \'\'hat bearing has the action observed upon the utility of yeast plants 

 in l)read making? Answer this question in your notes on this 

 evperinient. 



366 (Simple). Bread Mold (7?///;o/)»s nir/ricatis). — Use the hand 

 lens to examine the moldy Iji'ead without disturbing it, so as to see 



1 Stronp: oosin solution may be used, and it leaves the Bacteria with a 

 more litVHke appearance, ttinu^h not so sharply defined. If the prepara- 

 tion is .stained with gentian violet, washed, and thoroughly dried, Canada 

 batsam may be used upon it and the preparation thus he made permanent. 



- The lea'^Iii'r should draw upon the board the characteristic form and 

 striations of starch grains to be found in the yeast cake, so tnat they may 

 not be niisliiken for the yeast plants. 



