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 

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