GLIDING GROWTH AND THE BARS OF SANIO 
J. G. Grossenbacher 
Introduction 
By gliding growth is meant the independent elongation or enlarge- 
ment of cells in the growing zone which occurs, as some maintain, 
during differentiation and radial growth. The bars of Sanio are said 
to consist of cellulose and pectic materials in the form of bars or 
imperfect tubes which extend through two or more cells arising from 
the same initial in a direction at right angles to the plane of division. 
These bars have been studied chiefly as they occur in the xylem and 
phloem of trees, but have also been shown to occur in the more super- 
ficial cells of woody plants, where they extend parallel to the surface 
instead of as radii, as is the case with those arising in the cambial 
zone of trees. 
The bars arising in the cambium have been brought into discus- 
sions to refute the contention that certain cells on arising from the 
cambium undergo elongation during differentiation, as well as in studies 
on the phylogenetic relationship of some Coniferae. In investigations 
into the nature and activity of the cambial sheath the bars have also 
been used. It seems, therefore, that gliding growth and the bars of 
Sanio have been of much interest to botanists during many years. 
The present discussion aims to contribute some concrete evidence on 
the subject of gliding growth and at the same time to make brief 
mention of the related literature. 
Some Historical Aspects 
Most of the earlier investigators who incidentally studied this 
matter in connection with the differentiation of the cells from the 
cambium infer that gliding growth occurs, but their inferences were 
usually not based on sufficient tangible data.^ 
1 Trecul, A. Origine et development des fibres ligneuses. Ann. Sc. Nat. Bot., 
3. Ser. 19: 63-74. 1853. Hartig, Th. Ueber die Entwicklung des Jahrringes der 
Holzpflanzen. Bot. Zeit. 11: 553-60; 69-79. 1853. Velten, W. Ueber die Ent- 
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