94 IOWA ACADEMY OF SCIENCES. 



P. rubigo-vera, (D. C), Winter on Hordeum jubatum, Triticum vulgare, 

 Elymus Canadensis. 



P. co7-onata, Corda. On Avena sativa. 



P. sorghi, Schw. on Zea mays. A destructive species in some years. 



P. vexans, Farlow on Bouteloua racemosa. 



UsTiLAGiNE^. Ustilaga Maydis (D. C.) Corda on Zea mays. 



Smuts. Uslilago Madis on Zea mays. All varieties more or less, 

 but it is much more severe on some than others. "In 1889 the experiment 

 station had a row of corn, the seed of which came from Phillipine Islands. 

 The growth was vigorous; in height it exceeded by several feet the tallest 

 corn on the ground, produced well developed nodal roots. Not only were 

 the blades and sheaths badly infested with corn smut, Puccinia sorghi, 

 but many of the stems, sheaths and nearly every plant in the row was 

 smutted." The row adjoining this one had some smut, but no more 

 than other varieties grown some distance from it. 



U. Hordei on Hordeum vulgare. 



U. avence on Avena sativa. 



U. tritici on Triticum vulgare. 



U. bromivora var. on Bromus breviaristatus. 



U. panici miliacei (Pers.) Wint. on Panicum capillare. 



U. neglecta, Niessel, on pigeon grass [Setaria glauca)\ a very common 

 species. It is sometimes thought to cause abortion in Iowa. There is little 

 foundation for the opinion. 



Tilletia striajformis on Timothy {Phem j^fatense); Blue grass [Poa i^ra- 

 tensis) affects leaves and sheaths as well as parts of the flower. 



T./oetens (B. & C), Trelease on wheat [Triticum vulgare), (Bessey.) 



Urocystis agropyri on Wild rye, (Elymus canadensis); a very common 

 species. 



BACTERIA OF MILK, CREAM AND CHEESE, WITH EXHIBITION 

 OF CULTURES. 



ABSTRACT BY L. H. PAMMEL,. 



Some twenty or thirty different cultures were exhibited, partly obtained 

 from milk, butter and. cheese and some from rotting beets etc. The 

 method of obtaining pure cultures with gelatin and agar cultures was 

 explained. Thea ction of some of the bacteria on milk is rendering milk 

 sour. The souring of milk is not due to a single germ, but a large num- 

 ber have the power of changing milk sugar into lactic acid. Of the many 

 lactic acid germs some are especially important in giving the proper 

 aroma to cream, and the butter made from it. Certain species of bac- 

 teria render cream bitter. The old Clostridium butyricum was once sup- 

 posed to be the cause of bitter taste in butter. It has been shown that 

 this germ does not render butter bitter, but there are a number of quite dif- 

 ferent germs which may cause such changes. Certain peculiar flavors are 

 also due to the action of germs. 



