SOME TYPES OF FLOWEELBSS PLANTS. 227 



ture in a wide-mouthed bottle whioli holds one or one and a half pints, 

 stopper very loosely i and set aside for from 12 to 24 hours in a place in 

 which the temperature will he from 70 to 90 degrees. Watch the liquid 

 meantime and note : 



(a) The rise of bubbles of gas in the liquid. 



(6) The increasing muddiness of the liquid, a considerable sediment 

 usually collecting at the end of the time mentioned. 



(c) The effect of cooling off the contents of the bottle by immersing it 

 in broken ice if convenient, or if this is not practicable by standing it for 

 half an hour in a pail of the coldest water obtainable, or leaving it for an 

 hour in a refrigerator, afterwards warming the liquid again. 



(d) The effect of shutting out light from the contents of the bottle by 

 covering it with a tight box or large tin can. 



(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. 



(/) 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. 



{g) The smell of the liquid and its taste. 



277. 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 micro- 

 scope affords. 



Note: 



(o) The general shape of the cells. 



(6) 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, 198. 



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 red ink. Note the proportion of cells which stain at first 

 and the time required for others to stain. Repeat with yeast which has 



> If the cork is crowded into the neck with any considerahle force, pressure of gas 

 and an explosion may result. 



' See Huxley and Martin, under Torula. 



