THE AMERICAN BOTANIST 111 



number is devoted to an annotated list of plants collected by 

 Dr. Bailey in China in 1917. This covers nearly fifty pages. 

 Among the plants listed are 20 new species, 15 new varieties 

 and various new combinations of names. A number of the 

 interesting finds are illustrated. In addition to the scientific 

 information conveyed, the publication is of interest for the 

 number of common weeds listed. The Chinese gardener is 

 bothered with the purslane, chickweed, curled dock, mouse- 

 ear chickweed, several smartweeds, pigweeds, sorrel, butter- 

 cup, shepherds purse, pepper grass, and many others less well 

 known but fully as pestiferous. 



The mention of yeast usually suggests that pasty square 

 purveyed by the corner grocery and used in bread-making and 

 in other popular but forbidden American indoor sports, but 

 the term is far more inclusive. There are more than five 

 hundred species of yeast; the kind used for making bread is 

 only one of the number. Several yeasts used in beer making 

 have been cultivated in a pure state for hundreds of years. 

 Of the others, a large number, of course, are found in wines 

 and other fermented beverages, but they may occur almost 

 everywhere — on the soil, floating in the air, in the interior of 

 potato bugs, in the human intestines, in the lungs, in cheese, 

 raw sugar, milk, sour kraut, and in many skin diseases, in- 

 cluding cancer. Under the microscope yeasts are recognized 

 as oval or spherical bodies of minute size which ordinarily 

 reproduce by putting out small projections of the protoplasm 

 known as buds. The buds ultimately separate and form new 

 plants. Under special conditions, yeasts form within their 

 cells, small bodies known as ascospores and such spores may 

 also be formed by the conjugation of two separate cells. 

 When yeasts were first studied they were thought to be the 

 reproductive bodies of various fungi. This seemed especially 

 plausible since yeasts, themselves, may form chains and rib- 



