416 DR. P. GROOM AND MR. W. RUSHTON ON THE STRUCTURE 
4-6 similar cells forming a uniseriate series; sometimes the marginal cells, 
or rarely some internal cells, are ray-tracheids. The ray-tracheids are not 
abundant (fig. 13). 
The wniseriate rays are mainly composed of ray-parenchyma, whose cells 
in tangential section are vertically elongated, with an oval lumen and an 
oblong-oval contour ; these outlines are disturbed by the bulging in or out 
of the large pit-closing membrane. In some of these rays ray-tracheids are 
numerous (fig. 17). The length of the ray-parenchyma cell is equal to the 
radial width of 4-6 wood-tracheids in the radial spring-wood, and 2-4 in 
the summer-wood. 
PINUS LONGIFOLIA, Row, 
Pinus longifolia, the chir or long-leaved pine, is a three-needled species 
whose geographical distribution is interesting. According to Gamble (1902) 
and Brandis (1907) the tree flourishes in sub-Himalayan tracts and outer 
Himalayas. In the drier western region extending from Afghanistan to 
Nepal, it forms extensive pure forests at altitudes ranging from 1,500 to 
6,900 and occasionally 7,590 feet, but dees not grow in the inner valleys. 
In the moister eastern region it is less common, is often mixed with Shorea 
robusta, and in Sikkim is usually on dry southern slopes at altitudes between 
1,000 and 3,000 feet. Thus this pine shows greatest success in regions that 
are least moderately dry, and Gamble points out that transplants will not 
endure a wet soil. In the drier western region its thick rough bark suggests 
the xerophyte and. the light-demanding plant, in the moister eastern regions 
its bark is thinner. The suggestion has been made that its limited distribu- 
tion in the eastern region is due to the rainfall being too heavy. The deep 
tap-root confers an ability to obtain moisture in dry places, and its capacity 
in this direction is doubtless enhanced by its power of flourishing as a sub- 
deciduous tree ; for Gamble described the chir pine as more or less deciduous, 
while according to Brandis its needles remain on the trees for two or three 
years. In addition to its moderately xerophilous tendency this pine is 
exceptional in that it naturally occurs within the limits of the tropical 
climate, and “ will thrive in the Indian plains, even at Calcutta " (Gamble, 
loc. cit.). Thus some interest also attaches to the structure of the leaves and 
wood. 
A. Macroscoric FEATURES (naked eye). 
The light eoloured sap-wood contrasts with the red- or pink-brown heart- 
wood. Annual rings and resin-ducts are very distinct to the naked eve. 
The number of rings to the inch radius varies according to Gamble from 
2 up to 20; in our specimen there were 9. In each annual ring the summer- 
wood is rather abruptly marked off from the spring-wood. There is con- 
siderable variation in the proportions of the spring- and summer-wood 
forming one annual ring; in our specimen the summer-wood formed a 
