about twenty-four hours the yeast has become active as is shown 

 by frothing and the budding of the Torulae observed under the 

 microscope. This active yeast is sprinkled all over the plant, 

 care being taken to wet the bodies of as many aphides as possi- 

 ble. Over the plant is placed a bsll jar to isolate it from others. 



April II. — No effects noticed. Sowed more of the same 

 yeast. 



April 1 8. — The soil in the flower-pot has been allowed to 

 become quite dry. The larger leaves of the plant have turned 

 yellow, and upon these are nearly all the aphides. Counting as 

 carefully as possible, the number is found to be three hundred 

 and fourteen. The glass cover is removed and nearly all the 

 aphides are brushed off, and the plant allowed a few days to 

 recuperate. 



Experiment No. 5. — May i. — Sowed yeast procured direct from 

 the bakery upon the same plant as in No. 4. Upon the plant are 

 fifty-five aphides, mostly small. The plant is placed in a close 

 Wardian case where there is an abundance of moisture. 



May 6. — A mold (Mucor) has made its appearance upon all 

 parts where the yeast adheres. The aphides are nearly all dead 

 or dying. One aphis is found alive held to the stem of the plant 

 by a pasty mass of yeast. 



May 16. — Only three aphides alive ; the mold has seriously 

 injured the plant. 



Experiment No. 6. — May 26. — Sowed yeast from the same 

 bakery as in No. 5 upon the aphides on a healthy young plant of 

 same kind and size as No. 4. This time the plant was not 

 treated differently from others in the same room except being 

 thoroughly sprinkled with yeast. 



June 3. — Aphides as numerous as ever. No dead ones seen. 



Experiment No. 7. — To ascertain whether any fungoid growths 

 could be developed from the dead aphides in No. 5, two of them 

 are placed on a bit of clean, broken plant crock sufficiently moist- 

 ened, which is covered with a small bell glass, the rim of which 

 rests in a shallow vessel of water to isolate the experiment as 

 completely as possible. The experiment commences May 5, at 

 2 p. M. On May 6, at 3.30 p. m., some mycelium is visible on the 

 body of an aphis. 



May 9. — A number of upright hyphae have fruited ; the 

 quantity of fruit is very small and not sufficient to determine 

 what the mold is with certainty, but it appears to be a Mucor. 



