262 STUDIES ON FKKMKXTATIOX. 



work of M. Van Tiegliem {Annalcs Scientifques de Vilcole 

 Normale, vol. vi.) may be consulted. 



The possibility of living without oxygen, in the case of 

 ordinary moulds, is connected with certain morphological 

 modifications which are more marked in proportion as this 

 faculty is itself more developed. These changes in the vegeta- 

 tive forms are scarcely perceptible in the case of penicilliuni 

 and mycoderma vini, but they are very evident in the case 

 of aspergillus, consisting of a marked tendency on the part 

 of the submerged mycelial filaments to increase in diameter, 

 and to develop cross partitions at short intervals, so that they 

 sometimes bear a resemblance to chains of conidia. In mucor, 

 again, they are very marked, the inflated filaments which, 

 closely interwoven, present chains of cells which fall off and 

 bud, gradually producing a mass of cells. If we consider the 

 matter carefully, we shall see that yeast presents the same 

 characteristics. For instance, what can more closely resemble 

 the mucor of Plates V. and YI. than the saccharomyces of 

 Fiffs. .33 and 37 ? Have we not in each case ramified chains 

 of elongated cells or joints, more or less narrowed in the middle, 

 and shorter segments or cells dropping off at the constrictions, 

 and proceeding to bud in the liquid on their own account? 

 Moreover, the less oxygen there is present, the more marked is 

 the tendency to the formation of these budding cells, which 

 isolate themselves and soon drop off. Who could ever imagine, 

 in examining the ferment of mucor represented in Plate VI., 

 that its first germ was the ordinary mucor that is found 

 everywhere, with fine filaments, straight or ramified according 

 to the variety, which send up aerial hyphae, terminating in 

 little round heads bearing spores. So was it that in the 

 ferment of Plate XI. we could scarcely recognize the ramified 

 filaments of Figs. 33 and 37. 



It is a great presumption in favour of the truth of theoretical 

 ideas when the results of experiments undertaken on the 

 strength of those ideas are confirmed by various facts more 

 recently added to science, and when those ideas force them- 



