128 DIVISION II. COURSE OF DEVELOPMENT OF FUNGI. 



maintained at every instant of the successive stages of the development, in virtue 

 of which the later-formed member begins as a portion of the one which immediately 

 preceded it, was neglected or even expressly declared to be unattainable *. 



It is obvious that criticism could not alter this required condition ; and that it 

 is not at all impossible to carry it out is shown by many investigations, by those 

 especially which have been made since the appearance of the first edition of this 

 work, but also by some of a much earlier date. They have left much it is true still 

 to be done, but they have helped as a rule to clear up the subject, and have done 

 away with extravagant notions. The scientific method in the conduct of these 

 investigations was and is obviously that of strict observation of the whole course 

 of the uninterrupted development, the ascertaining the organic continuity of the 

 parts of the development at each instant of its course ; this is simply the method 

 by which we determine that the apple is a product of development of the apple-tree, 

 and that the tree is produced from the apple; the logic does not change with the 

 size of the objects or with our apparatus and manipulation. The technical expedients 

 adopted in applying this method to the Fungi depend on the particular case. The 

 use of the microscope is generally necessary on account of the small size of the objects 

 to be dealt with, and we must often follow the development directly under the 

 microscope, the objects being cultivated on a microscopic slide or in a moist chamber 

 and on a substratum which is at once sufficiently nutrient and transparent. The 

 juice of fruit carefully kept pure, decoctions of fresh animal excrement, saccharine 

 solutions with addition of ash-constituents, or gelatine saturated with the above 

 fluid matters have proved to be suitable substrata for most artificial cultures under 

 the microscope. Which is best in each particular case must be determined by 

 considering the habits of the species. A different method of cultivation to the one 

 here described must be adopted in the observation of most parasitic Fungi, as will be 

 shown in Division III. We are indebted to Brefeld especially for the perfecting of 

 the technical procedure and technical methods in the cultivation of Fungi and par- 

 ticularly in their cultivation under the microscope, after the guiding principles had been 

 already indicated by myself in the first edition of this work. 



Mistakes may be made and doubtful questions arise even in the use of the most 

 correct scientific method. Such of these as may be noticed in the sequel must not be 

 confounded by the student with theories of pleomorphism which are now obsolete. 



SECTION XXXV. As regards the terminology of the subject it may be observed, 

 that in Fungi as in other plants the development of a new bion very often begins 

 with a cell, which is detached from the parent or at least ceases to draw its 

 nourishment from it, and then has the power of further development if the conditions 

 are favourable. The origin and structure of such cells are very various, and are 

 characteristic in each particular case. But the general phenomenon remains the 

 same in all and requires therefore to be indicated by a general expression which 

 has reference only to it. Such an expression is the word spore (spora) which was 

 introduced by C. Richard and Link, and has continued to be used ever since in spite 

 of all attempts to supersede it. At the same time there were good reasons for these 

 attempts, which rested on the consideration that spores in the sense of Richard and 

 Link may be produced in a variety of forms on the 'same species and at dissimilar 

 places in the course of the development, and that it would be well to distinguish 

 these forms according to their structure, development, and homologies. Accordingly 

 A. Braun distinguishes in the chlorosporous Algae, for instance, between spores and 



1 See for example Bot. Ztg. 1867 p. 351 ; also De Bary, Ueber Schimmel u. Hefe, Berlin, 1873. 



