L. A. Boodle. 
56 
twigs were counted, and the numbers of leaves were as follows. 
There were 602 normal pairs of leaves, 1 20 double leaves and 6 
solitary leaves, i.e., 6 leaves each borne singly on a spur-shoot. 2 
One of the features of this case of concrescence is its simplicity. 
It is clear that only the two normal leaves are represented, and 
there appears to be no necessity to assume that any of the tissue 
in the region of concrescence is other than leaf-tissue. At any rate 
in a case like the present one, in which the apical growth of the 
shoot becomes arrested, it may be held that reduction in the 
bulk of the apical cone might involve the suppression of some 
Figs. 1-4. Austrian Pine (Piniis Laricio Poir., var. nigricans Pari.). 
Fig. 1. Transverse section of double needle : ep. hy ., epidermis and hypo- 
derm ; m., mesophyll; r.c., resin-canal; e. t endodermis; xy., xylem ; ph ., phloem. 
X about 30. 
F'ig. 2. Diagrams illustrating variable orientation of the double needles : 
a., twig or parent axis ; l., scale-leaf borne by the twig ; «., double needle borne 
by the spur-shoot in the axil of l. A, adaxial fusion ; 13, abaxial fusion ; C, 
oblique orientation. 
Fig. 3. Transverse section of a solitary leaf, showing the groove, g. 
X about 30. 
Fig. 4. Transverse section through the base of the same leaf, showing two 
protuberances, apparently the apex of the spur-shoot, a., and the rudiment of 
the second leaf, l. x about 30. 
1 Normal except that in a few cases one leaf was a good deal shorter than 
the other. 
* These solitary leaves will be described later. 
