CRITICISM OF FLEMMING 179 



protoplasm. I must say I think that Flemming was in 

 error when he regarded the image obtained with a bright 

 light and widely open diaphragm as the more correct ; for, 

 as has already been pointed out frequently by others, the 

 distinctness of the structures suffers very much from intense 

 illumination, which of course receives a natural explanation 

 from the fact that with a strong illumination our eye is no 

 longer able to distinguish the relatively slight differences of 

 light and shadow. 



I am therefore not at all of Flemming's opinion, that the 

 net-like connection of the filaments or fibrillae which becomes 

 apparent on diminishing the illumination is a result of the 

 image becoming indistinct, so as to produce the effect of the 

 filaments which run over one another appearing connected 

 together. As a rule, it certainly cannot be asserted that the 

 microscopic image is rendered less distinct by diminish- 

 ing the illumination ; on the contrary, any one can easily 

 convince himself that it thereby becomes much more 

 distinct and sharp. In any case the filaments running at a 

 higher or lower level could not lie simultaneously in the 

 plane of distinct vision, while net-like connections of the 

 threads in the same plane of focus can frequently be 

 demonstrated with the utmost certainty. All these reasons 

 place it beyond a doubt in my mind that Flemming's dislike 

 to the idea of a reticular framework is to be referred in the 

 main to a false estimation of the correctness of the micro- 

 scopic image. 



To this must be added a further reason, which I will 

 proceed to discuss rather more in detail. In studying 

 the reticular framework, a more or less confused fibrous 

 structure is usually very prominent. This depends on the 

 fact that now in one place, now in another, some of the 

 walls of the meshes are arranged for a greater or less 

 distance in a series one behind the other to form a sinuous 

 line, and thus give the impression of lines of some length. 

 Now it can be shown easily that the eye is better able to 

 observe delicate lines when they are long than when they are 

 short, so that the greater the distance for which the tracts of 

 the network have a linear arrangement in rows, the plainer 



