224 A. Barclay—On a new Species of Uredine [No. 2, 
the most injurious consequences to its welfare. The fungus is confined 
entirely to the leaves, the mycelium never being found in the tissues of 
the stems bearing affected needles. The mycelium is therefore not 
perennial. Before entering upon a description of the structure of the 
fungus and of its morphological relations to its host, it is necessary to 
give an account of the normal structure of the needle. 
Normal Structure of Deodar Needle—The transverse section of a 
young normal needle is broadly quadrangular, one angle being superior, one 
inferior, and two lateral ; the superior angle is truncated and grooved ; 
as the needle grows older, however, the upper angle becomes gradually 
flattened until at last the section of an old needle is more triangular 
than quadrangular (fig. 8). On each of the four sides of the young 
needle there are as a rule four longitudinal rows of stomata, and on 
either side of the needle a resin canal, one of which is always larger than 
the other, though both are of the same structure. The centre of the 
needle is occupied by the wood bundle, the xylem being below-and the 
phloém above. 
Looking next to the more minute structure of the tissues of the 
needle, it will be observed that the needle is clothed externally by a sin- 
gle layer of epidermis cells. Under this is a layer of thick-walled hypo- 
dermal cells, interrupted opposite the stomata, and double at the angles 
and between the stomata, where there is only space for a single cell; 
this layer is double also at each side of the resin canals. These cells 
are from three to four times as long as they are broad, and the epidermal 
cells are about one-third the length of the hypodermal cells. The resin 
canals are clothed internally by a layer of thin-walled epidermis cells 
supported externally at about three places by a second layer of similar 
cells: the whole is surrounded by a layer of’ sclerenchyma fibres, 
except where the canal is bounded by the hypodermal cells. Below the 
hypodermal layer follow large parenchymatous chlor ophyll-containing 
cells radially arranged. These cells internally abut against the cells of an 
endodermal sheath surrounding the central vascular bundle, much in the 
same way as that in which palisade cells of leaves generally abut against 
the spongy tissue. This parenchymatous tissue is loose with numerous 
large air-cavities. The cells of the endodermal sheath are closely conti- 
guous laterally, and are densely filled with starch grains. They are~ 
large cubical cells nearly twice as long as they are broad. The tissues 
enclosed by this sheath are :—(a) in the centre the xylem and phloém 
divided into two lateral divisions; the xylem being below: (b) beyond 
the phloém a group of much thickened sclerenchyma fibres: beyond 
these again and between them and the endodermis, (¢) a set of large 
water-containing cells with numerous bordered pits. Laterally the’place 
