vi PREFACE 



with other cases where the actual author is ignored, his Dame being 

 replaced by that of the compiler of some text-book from which the copy was 

 obtained i.e., some one who himself has done nothing more than copy. 

 Such a mode of procedure is in a high degree calculated to produce a 

 misty conception of the actual circumstances in the mind of the reader, 

 the more so because, as stated, no importance is attached to the occurrence. 

 DR. LAFAR has, however, set vigorously to work to combat this bad habit 

 by taking all his reproductions direct from the original sources, so that they 

 are clear and accurate representations of these originals. 



The subjects included in the present work have been dealt with in a 

 many-sided manner, the Botanical as well as the Technical and Chemical 

 aspects having been borne in mind, although preference has throughout 

 been accorded to the two latter. The style is flowing and clear, in many 

 places lively and picturesque, and I have read with interest even those 

 portions wherein I am not at one with the opinions of the author. The 

 attention devoted to the most recent developments of the subject gives a 

 special value to the book. 



Within the last two decades the study of Microbiology has made gigantic 

 strides, both in the pathological and the technical branches of the subject ; 

 and just as investigations into the Physiology of the higher plants gave the 

 first impetus to the establishment of Agricultural Experimental Stations in 

 all countries, so, in like manner, have the Physiology of Fermentation and 

 Technical Bacteriology called into existence, within the last few years, a 

 number of Stations and Laboratories for the development of those branches 

 of industry wherein micro-organisms play an important part. Formerly, 

 Chemistry exercised an undisputed sway over the whole of this realm, but 

 now Biology has won for itself a co-ordinate position therein a fact which 

 is now being recognised (although not yet to an adequate extent) in the 

 filling of professorships at the various Technical High Schools. An army 

 of eager workers has arisen, new technical journals have sprung into 

 existence, and a great number of treatises and books are published on the 

 subject every year. However cheering this may be in itself, the fact can- 

 not be gainsaid that a portion (unhappily much too large) of these publica- 

 tions ought properly never to have seen the light. It is true that an 

 intimate connection with practical conditions sets fresh tasks before the 

 investigator, and exerts on the whole a sufficiently stimulating influence ; 

 but, on the other hand, the same circumstance gives rise to the danger of 

 diverging into by-paths, and neglecting the strict scientific conditions of 



