GLIDING GROWTH AND THE BARS OF SANIO 
of the cambial sheath and which therefore continued to give rise to 
new xylem and phloem cells during a considerable period before its 
last derivative arrived at a position in the cambium where it was 
forced to become differentiated into a mature cell and cease further 
division. Such an argument not only tends to show that cells through 
which these bars extend have not glided on each other, since they 
arose from each other by division, but also indicates, as Raatz and 
later Nordhausen,^ Schoute,^^ and Miiller^^ maintained, that Sanio's 
simple hypothesis on the nature and method of origin of cells from the 
cambium does not cover the facts of cambial division as it occurs in 
our trees. Incidentally it may also be mentioned that since Raatz 
and others found these bars occurring in numerous and widely sepa- 
rated species of trees, and Petri^^ has more recently shown them to 
occur in the cultivated varieties of the grape when affected by a disease 
known as "courte none," they seem to have very little of phylogenetic 
significance in the conifers as maintained by Gerry^^ and others. 
Groom and Rushton^^ have recently also contributed to the question 
of the bars or rims of Sanio, 
Gliding Growth in Apple {Pyrus mains L.) 
While studying the development of the initial stages of crown-rot 
of apple trees in cross sections it was frequently noticed that the 
more or less regular radial rows of wood cells arising from correspond- 
ing rows in the cambial zone are separated by cells in their angles. 
The diameter of the intruding cells nearest the cambium was usually 
very slight and increased as the distance from the cambial zone in- 
creased. These intercahited cells were suspected of being some that 
^ Nordhausen, M. Zur Kentitniss der Wachstumsvorgange im Verdickungsringe 
der Dikotylen. Beitrage Wiss. Bot. 2: 356-400. 1898. 
Schoute, J. C. tiber Zellteilungsvorgange im Cambium, Verhandel. K. 
Akad. Wetensch, Amsterdam 9: Sect. 2, pp. 66, 1902. 
Miiller, C. Ueber die Balken in den Holzelementen der Coniferen. Ber. 
Deut. Bot. Gesellsch. 8: (i7)-(46), 1890. 
^2 Petri, L. Ricerche sulle cause dei deperimenti delle viti in Sicilia. i. Con- 
tribute alio studio dell' azione degli abbassamenti di temperatura sulle viti in rapporto 
air arricciamento. Mem. R. Staz. Pat. Veg., 1912, pp. 212, Roma. 
13 Gerry, E. The Distribution of the "Bars of Sanio" in the Coniferales. 
Ann. Bot. 24: 119-23. 1910. 
1^ Groom, P., and Rushton, W. Structure of the Wood of East Indian Species 
of Pinus. Jour. Linn. Soc. Bot. 41: 457-90. 1913. 
