30 GENERAL MORPHOLOGY. 



phology of the Eumycetes, everything necessary to enable the 

 following chapter to be readily intelligible. In the event of 

 any reader desiring to learn more with regard to the structure 

 of fungi in general, the handbook compiled by W. Zopf (X.) 

 can be consulted, after which, he may profitably study the work 

 of A. DE Bary (L), which still — fifteen years after its first 

 appearance — remains the standard work on mycology. The 

 results of the labours of 0. Brefeld, which in many respects 

 were based on other fundamental views, are contained in a work 

 published by F. von Tavel (I.). 



With regard to all concerning the general physiology and 

 biology of the Eumycetes, the reader can rely on the first of the 

 tlu^ee books named. During the period of rather more than 

 a decade that has elapsed since it was completed, the subject has 

 made considerable advances in five different directions, viz. 

 the chemistry of the cell membrane, the requirement of mineral 

 nutrient substances, the stimulative influence of light, chemo- 

 tropism, and the production of enzymes. These questions alone 

 will be treated in the three following chapters of the present 

 work, since it is no part of the author's purpose to supplant 

 existing good books. Furthermore, the reader will quickly see 

 that there has been no stringent limitation to the subjects 

 cited, but that every opportunity has been taken in order to 

 gain a general view during the necessary consideration of 

 particular points. When presented in conjunction with the 

 treatment of questions possessing visibly practical importance, 

 certain general explanations will be more readily appreciated by 

 the reader than if given at the commencement of the book, 

 where they would either pass unnoticed or fail to interest. 



