RESULTS OF SCIENTIFIC RESEARCH IN PRACTICE. 227 



to instruct the younger generation in the true understanding 

 and the proper application of his discoveries. Such institu- 

 tions have now been established in -almost all countries, and 

 are partly private and partly supported by state ; they have 

 already produced a number of able teachers, analysts, and 

 technologists, who are working with energy and judgment 

 with a view to more widely circulate in science and in practice 

 the views of the Danish investigator. 



Hanserfs investigations have indirectly exercised an in- 

 fluence in connection with the dairy ; as was mentioned 

 in a previous chapter, pure cultures of lactic acid bacteria 

 have been successfully employed for the souring of cream. 

 Finally, also, in the tobacco fermentation, Schloesing and 

 Suchsland have made experiments with the view to produce 

 a definite aroma in tobacco leaves by the addition, during 

 the fermentation, of pure cultures of certain species of 

 bacteria. 



The idea which underlies all these reformatory investiga- 

 tions, is the principle which has been recognised and carried 

 out for centuries in horticulture and agriculture, namely, that 

 in order to obtain the desired species of plant, the pure seed 

 should be sown free from the seeds of all other plants. 



