TYPES OF CRYPTOGAMS; THALLOPHYTES 267 



(e) The result of filling a test-tube or a very small bottle with 

 some of the syrup-and-yeast mixture, from^ which gas-bubbles are 

 freely rising, and immersing the small bottle up to the top of the 

 neck for fifteen minutes in boiling water. Allow, this bottle to 

 stand in a warm place for some hours after the exposure to hot 

 water. What has happened to the yeast-plants? 



(/) The behavior of a lighted match lowered into the air space 

 above the liquid in the large bottle, after the latter has been standing 

 undisturbed in a warm place for an hour or more. 



(jr) The smell of the liquid and its taste. 



321. Microscopical Examination of the Sediment.^ — Using a very 

 slender glass tube as a pipette, take up a drop or two of the liquid 

 and the upper layer of the sediment and place on a glass slide, cover 

 with a very thin cover-glass and examine with the highest power 

 that the microscope affords. 



Note: 



(a) The general shape of the cells. 



(J) Their granular contents. 



(c) The clear spot, or vacuole, seen in many of the cells. 



Sketch some of the groups and compare the sketches with 

 Fig. 197. 



Eun in a little iodine solution under one edge of the cover-glass, 

 at the same time touching a bit of blotting paper to the opposite 

 edge, and notice the color of the stained cells. Do they contain starch ? 



Place some vigorously growing yeast on a slide under a cover- 

 glass and run in a little eosin solution or magenta solution. Note 

 the proportion of cells which stain at first and the time required for 

 others to stain. Repeat with yeast which has been placed in a slen- 

 der test-tube and held for two or three minutes in a cup of boiling 

 water. 



With a very small cover-glass, not more than three-eighths of an 

 inch in diameter, it may be found possible by laying a few bits of 

 blotting paper or cardboard on the cover-glass and pressing it against 

 the slide to burst some of the stained cells and thus show their thin, 

 colorless cell-walls and their semi-fluid contents, protoplasm, nearly 

 colorless in its natural condition but now stained by the iodine. 

 1 See Huxley and Martin's Biology, under Torula. 



