Development of Mechanical Tissue. 513 
manifested in their histology. The same may be said of 
Laborie’s work 1 , although he used fruit-bearing and vegeta- 
tive shoots, instead of comparing fruit-stalks with vegetative 
shoots. This brings him nearer to the purpose of this paper, 
although he kept in view the study of adaptation to use as 
the principal end of the work, and made a more detailed 
histological study than is here contemplated. He found 
a marked preponderance of parenchymatous tissue, both 
cortical and medullary, and a more feeble development of 
the fibrovascular bundles, in the fruit-bearing shoot. The 
primary bast was nearly always lacking in the fruit-bearing 
shoot, or if present it was thin and scattered. In this shoot 
also the crystal-bearing cells and sieve-tubes were more 
abundant ; and in the xylem there were fewer fibres, their 
place being taken by wood-parenchyma. 
The first paper I found in which the influence of fruit- 
bearing on the structure of the woody axis was considered 
was one by Sorauer 2 , who, in 1880, published the results of 
an investigation on the effect of fruit-bearing on the develop- 
ment of wood in some fruit-trees. I regret that I have not 
had access to the original paper, but I have made use of two 
excellent abstracts, one in the Bot. Centralblatt for 1880, 
p. 453, and one prepared for me by Prof. F. C. Newcombe 
while at Leipzig. The latter paper has been especially helpful, 
since it gives the gist of Sorauer’s thought in a few concise 
quotations. 
Sorauer made comparative measurements of the diameters 
of internodes in shoots of wild and cultivated pear-trees, and 
also of fruit-bearing and leafy shoots on cultivated trees. 
From these measurements he concluded that cultivated 
varieties are weaker ( weicher ) than wild ones, and that fruit- 
bearing shoots are weaker than leafy ones ; also, that in any 
1 Laborie, Note sur les variations anatomiques et la differentiation des rameaux 
dans quelques plantes, Compt. Rendus, 1883, 97 ; 342. 
2 Sorauer, P., Beitrage zur Kenntniss der Zweige unserer Obstbaume. Forsch- 
ungen auf dem Gebiet der Agrikultur-Physik, 1880, Band III, Heft 2. Ref. in 
Bot. Centralblatt, 1880, 1; 453. 
