OF THE WOOD OF INDIAN SPECIES OF PINUS. 461 
given by Penhallow (1907) shows that the number of longitudinal rows of 
bordered pits on the radial walls is not determined by radial width of lumen, 
as the haploxylie species are mainly uniseriate, and that paired or biseriate 
pits occur only in two haploxylie species with widest tracheids, But in the 
diploxylie species Penhallow’s statistics show that the wide tracheids of 
P. Tueda and P. palustris have only uniseriate pits, whereas many with 
narrower tracheids have uniseriate or occasionally paired pits, or even 
1-2-seriate pits. Systematic affinity undoubtedly is one of the determinant 
factors. In the Indian species the point worthy of note is that P. excelsa 
and P. Gerardiana show the uniseriate arrangement prevalent in the 
haploxvlie species. As is well-known, in one and the same species width 
of tracheid may appear to determine the number of rows, because in the 
summer-wood (of all the Indian species also) the radial pits are uniseriate. 
(е) Sanio's Rims. 
The radial walls of the spring-tracheids of the secondary wood of 7'inus 
show certain narrow, transverse, or more or less curved strips that appear 
lighter than the vest of the wall and generally stain less deeply than this 
when treated with certain solutions (phloroglucin and hydrochloric acid, or 
safranin) which stain lignified membranes. (Sometimes, when sections 
deeply stained with safranin are decolorized, differentiated by clove oil, and 
mounted in Canada balsam, these bands are on the other hand the parts that 
retain the stain most deeply.) 
Now Sanio showed that in Pinus sylvestris the differentiation of bordered 
pits is preceded by the delimitation of certain oval or elliptical patches 
bounded above and below by curved bow-like lines. According to Sanio it 
is only within such oval patches that bordered pits arise ; hence he termed 
each patch a “ primordial pit " and we term it “ the primary pit-area.” In 
such an area Sanio showed that one bordered pit, or two side by side, may 
arise, but usually the primary pit-area in the spring-t racheids is not 
completely covered by the pit or pits ; there remains behind a margin above 
and below. According to Sanio’s work it is these unoccupied margins of 
the primary areas that coincide in position with the above-mentioned bands 
that are seen in radial section. Consequently the name * Sanio’s rims" 
may be given to the structures causing the band-like appearance. According 
to Sanio sometimes a bordered pit does occupy the whole of the primary 
pit-area, and with this fact may perhaps be correlated the absence of any 
distinct Sanio’s rims in a number of cases. When the primary pit-areas 
are in contact, the two contiguous Sanio’s rims are naturally “ fused” and 
form a band that is transverse and single, except possibly at the two lateral 
edges where the natural curvature of each original boundary of the area 
causes the band to fork. When, on the other hand, the primary pit areas 
