THE LIFE HISTORY OF SACCHAROMYCETES. 253 



met with in nature. Neither HAXSEN (LIX.) nor BEIJE- 

 RINCK (XXVIII.) was able to confirm Boutroux's communication. 

 Another remarkable result obtained by this worker (III.) was 

 that insects play a more important part than wind in the con- 

 veyance of yeast cells that are unable to invert saccharose, the 

 converse being the case with yeasts capable of inversion. 



ROMMIER (I.) is of opinion that Sacch. apiculatus passes the 

 winter in honeycomb; but neither these nor any other yeast 

 cells have been discovered in comb by Boutroux, Hansen, 

 Beijerinck, or Klocker. Of course it is possible that a few 

 isolated yeast cells or other micro-organisms may be found 

 occasionally in any situation ; but we are now concerned solely 

 with large quantities and constancy of occurrence. 



BERLESE (IV.) asserted that the digestive canal of insects forms 

 the true winter resort of the Saccliaromycetes, and that Hansen 

 was in error when he located this resort in the soil ; and he 

 claimed that the cells pass the winter in flies (especially in Italy). 

 This statement may, however, be disregarded, since the insects do 

 not themselves pass through the winter in the perfect state 

 (imago) in Europe, except in the most southerly districts (and 

 therefore not at all in the largest part of Italy) ; in addition to C 

 which he only succeeded in finding a single fly containing Saccharo- 

 myces among 150 examined. He also states that the cells pass v 

 the winter in ant-runs in hollow trees and woodwork a circum- 

 stance of no importance even if true, because these habitats are 

 so rare in comparison with the area pres3nted by the soil that 

 even if every ant's dwelling contained Saccharomycetes their 

 number would be insignificant in comparison with those found 

 in the soil. Moreover, Klocker carried on a large number of 

 experiments on the behaviour of insects toward /Saccharomycetes, 

 and found that insects are devoid of importance as a winter 

 habitat, at least in Europe north of the Alps. 



That Saccharomycetes are able to pass without injury throug 

 the alimentary canal of various animals has been demonstrate 

 by several workers, e.g., by KLOCKER and SCHIONNING (VIII.) i 

 the case of insects and birds ; by BERLESE (IV.) with insects ; an 

 by CORDIER (I.) in the case of insects and animals. Consequently 

 the micro-organisms in question may also be disseminated by 

 these means. 



272. Later Experience on the Life History of 

 Saecharomycetes. 



The starting-point and basis of the foregoing researches on the 

 life history of the true /Saccharomycetes were constituted by the 

 results of Hansen's experiments on /Sacch. apiculatus. However, 

 though the Hansen theory sufficed to explain all the observations 

 made with respect to that species, it was, in several cases, not 



