6 



THE AMERICAN MONTHLY 



[Jan., 



a small glass of dilute alcoliol. According to a recent 

 communication by Effront, squares of clay may be used 

 instead of the gypsum. The form of the substratum is 

 immaterial. 



Cultivation in sterilized water in a test-tube, or on 

 moistened filter-paper, will — ceteris paribus — result in a 

 formation of spores in the yeast. Eor the determination 

 of species, the method described above must be recom- 

 mended, because it is one of the factors in Hansen's* es- 

 tablishing of his species. It is still an open question 

 whether the different ways of spore-cultivation affect 

 the results in regard to the time, at constant tempera- 

 tures, in which spores are formed. — Other points, con- 

 cerning spore-cultivation of pure cultures, will be men- 

 tioned below. 



Remarks on the spokes. — A table above indicates the 

 results and how to use them. The spores are, in the cul- 

 tivated forms very refractive compared with those of the 

 wild forms'^'. Their size and number varies somewhat : 



KINDS OF YEASTS. 



1. S. cerevisise I 



2. S. pastorianus I.... 



3. S. pastorianus II... 



4. S. pastorianus III. 



5. S. ellipsoideus I 



(5. S. ellipsoideus II... 



7. S. marxianus 



8. S. exiguus 



9. S membrana'faciens 



10. S. ludwigii 



11 S. anomalbs 



[All of Hansen.] 

 12. S. hansenii Zoph. . 



Spores. 



Dla. 



2,5-6 



1,5-5 



2-5 



2-4 

 2-4 

 2-5 

 2-4 

 2-4 



No. 



1-5 



1-10 



1-7 



1-10 



1-4 



1-4 



2-3 



'i-8 



2-4 



KINDS OF YEASTS. 



Spores 



Dia. 



No. 



13. S 



14. S, 



15. S 



16. S 



17. S 



,18. S, 



19. S 



20. S 



21. S 



22. S 



2 5 



2-4 



. jcBrgensenii Las- 



che I 1- 



, cong 1 oraeratus | 



reess 



. albicans Reess 1 



, Reessi David 3 



. galacticola Perot. 1 



et Rib 2-4 



I. of Will 1,5-5 1-5 



II. of Will 2-4 1-4 



minor Engel 3 | 2-4 



ilicis Groeuld. ... I 



aquifolii Groeu.j | 



*Wild forms if an expression now commonly used of the forms that are not 

 cultivated. This term is intimately connected with the post-pasteurean view 

 of these plants, and with the question of pure cultures and of pure yeast. 

 Pure cultures, such as we know them to-day, were not known to Reess (1870) 



