The Distribution of the ‘Bars of Sanio 5 in the 
Coniferales . 1 
BY 
ELOISE GERRY, M.A. 
With Plate XIII. 
T HE £ bars or * folds ’ of cellulose, which, when stained with haema- 
toxylin, are especially obvious as horizontal or more or less 
semicircular markings in the tracheide walls of a radial section from such 
a Conifer as Pinus silvestris , L., were described by Sanio in 1872. 
Although these structures were named the * Bars of Sanio ’ from him, and 
in spite of the fact that he declares that ‘ diese scheibenformige Ver- 
dickung der Scheidewand ist bisher iibersehen ’, 2 we find that in 1849 
Goppert had indicated their presence in two drawings, one of Cryptomeria 
jciponica , and the other of Cupressinoxylon aequale , which he used to illus¬ 
trate his ‘ Monographic der fossilen Coniferen \ 3 
Little attention, however, has been directed towards the bars of 
Sanio, although their presence in Pinus silvestris , L., is indicated in the 
chapter concerning coniferous woods in Zittel’s * Handbuch der Palaeonto- 
logie \ 4 Again, in 1898, Dippel mentions them in his chapter entitled 
‘ Entstehung der behoften Poren \ 5 But here, as before, Pinus silvestris, L., 
is the only species cited. 
It is the purpose of this paper to discuss their distribution from 
observations made upon all the genera of living Conifers, together with 
some fossil forms. For this study radial sections 5 fx in thickness were 
used. The bars, since they are composed of cellulose, take a blue stain with 
haemotoxylin, and therefore stand out clearly from the red background 
obtained by the general staining of the tracheide walls with safranin. In 
every case they appear most abundantly in the thin-walled tracheides in 
the spring-wood of the stem and in the root. Often when they are ab¬ 
sent or difficult to discern in the stem they are found without difficulty 
in the root. 
1 Contributions from the Phanerogamic Laboratories of Harvard University, No. 21, 
2 Jahrbiicher fiir wissenschaftliche Botanik, Bd. 9, S. 78, 1873-1874. 
3 Leiden, bei Arnz & Co., 1850. 
4 II. Abtheilung, Miinchen u. Leipzig. 
5 Das Mikroskop, zweiter Theil, Braunschweig, von F. Vieweg & Sohn, 
[Annals ^of Botany, Vol. XXIV. No. XCIII. January, 1910.] 
