CHAPTER XV, 
ANATOMICAL EVIDENCE. ° 
In the previous chapter it has been shown that early embryological detail 
is an insecure guide for purposes of comparison: that segmentation is not 
related with any general constancy to the origin of the appendages: also 
that the anatomical regions of the mature part are not defined with any 
constancy by early segmentations at the apex. It remains to enquire in 
what way the anatomical’ characters of the mature parts will affect the 
questions discussed, and especially whether they tend to support or to 
refute the strobiloid theory as put forward in Chapter XI. 
The most pregnant change in anatomical view effected during the last 
half century has been caused by the introduction of the Stelar theory of 
Van Tieghem. Prior to it the individual vascular strand, pursuing its 
course from the appendage into the axis, was regarded generally as the 
structural unit of the vascular system of the whole shoot. This was a 
natural consequence of that “detailed investigation of the course of the 
individual vascular strands which was initiated with such success by 
Naegeli, and extended by many other writers. The position taken up by 
these observers is admirably summarised in the Comparative Anatomy of 
De Bary: from his account it will be seen that the method of anatomical 
study, as well as its result up to 1877, was such as to give prominence 
to the individuality of the leaf: the facts as there stated might almost be 
read as an expression of phytonic theory in terms of internal structure, 
since the chief aim was to follow downwards to its termination each 
individual strand of the leaf-trace. A phytonic view of the facts was 
never explicitly set down by De Bary, though the under-current of 
thought seemed clearly to lead to an analytical rather than an integral 
view of the construction of the shoot. 
But very soon this was corrected, on general and external grounds 
rather than on those of anatomy, by Sachs: for in his Lectures on the 
Physiology of Plants (1882), he strongly insisted on the contemplation of 
the shoot as a whole. It is impossible to say how far this may have 
