HISTORICAL 133 



The investigations of Seiter l and especially those of Hansen, 

 Klocker 2 and Schionning have established with a remarkable pre- 

 cision that these investigators were led astray by impurities in their 

 cultures. They have shown that the yeast-like structures of Dema- 

 tium never sporulate, and that the leavening agent of sake consists, 

 besides Aspergillus oryzae, of a yeast in no way related to the mold 

 which induces the fermentation. The same authors have made 

 repeated experiments to change yeasts into molds and molds into 

 yeasts under conditions such as those which obtain in nature. They 

 have never secured reliable results. 



However the question of the origin of the yeasts from molds has 

 been raised anew by the investigations of Viala and Pacottet 3 on 

 Gloeosporium ampelophagum and Gloeosporium nervisequum. One of 

 these fungi, Gl. nervisequum presents perithecia which have been ob- 

 served by Klebahn who has classed it among the Ascomycetes spheri- 

 ceae. The other, the Gl. ampelophagum, on account of the presence of 

 pyknides, organs characteristic for the Spheriaceae, has also been 

 placed in the same family of ascomycetes although perithecia have 

 never been observed. According to Viala and Pacottet these two 

 microorganisms are able to develop, when placed in suitable nutrient 

 media, into true yeasts, capable of setting up the alcoholic fermenta- 

 tion and forming endospores identical in all respects with those 

 formed by Saccharomycetes. These yeasts become fixed after culti- 

 vation in the same medium, and find it impossible to return to the 

 mycelium state. Viala and Pacottet conclude that yeasts originate at 

 the expense of more highly developed fungi and think that, if it is im- 

 possible to change the industrial yeasts into mycelial conditions, it 

 is due to a long existence in the state of yeasts and it has become im- 

 possible to change. Thus according to these investigators the yeast 

 sporangium may not possess the value of the asc but the endospores 

 may result from an encystment of protoplasm without other mor- 

 phological significance. 



Guilliermond 4 in studying this question and trying to reproduce 

 the results of Viala and Pacottet established that impurities in cul- 



1 Seiter, O. Studien ii. d. Abstammung d. Saccharomyceten. Cent. f. Bakt. 

 2, 1906. 



2 Klocker, A., and Schionning, H. Que savons-nous sur 1'origine des Sac- 

 charomyceten. C. R. du Lab. de Carlsberg, 55, 1896. 



3 Viala, P. and Pacottet, P. Nouvelles recherches sur PAnthracnose. Rev. 

 de viticulture, 1905. Levures et kystes des Gloeosporium. Ann. Inst. Agr. 5, 

 1906. 



4 Guilliermond, A. A propos de 1'origine des levures. Ann. mycologici, 5, 

 1907; Recherches sur le dev. du Gl. nervisequum et sa pretendue transformation 

 en levures. Rev. gen. de Botanique, 20, 1908. 



