50 LLOYD. 



very wise procedure, inasmuch as Heer's material, judging 

 from his plates, does not offer any evidence in regard to the 

 body of the twigs, but only as regards the ends, and even as to 

 this the material is meagre. In all probability more extended 

 search would discover that Heer's Leptostrobtis possessed the 

 two arrangements of leaves, scattered and fasciculated, since 

 this is true of Fontaine's forms described under this genus. 



It may be further remarked that with Leptostrobtis Fontaine 

 found other fossils which referred to a new genus, Laricopsis. 

 These in general are larch-like, but like Leptostrobits, possess 

 two kinds of leaves — fasciculate and scattered. Fontaine draws 

 attention to the fact that the young shoots of Larix occasionally 

 produce the scattered or primarily leaves and compares them 

 to the permanent scattered leaves in Laricopsis^ the probable an- 

 cestral form from which the Larch has been derived. It is 

 reasonably certain, therefore, that in Leptostrobiis and Laricopsis 

 we have closely allied forms which lived together and were the 

 forerunners of the Pines on the one hand and the Larches on 

 the other. 



As to the causes which bring about the hypertrophy of the 

 scale-leaves in Pimis poiiderosa it may be said that the increase 

 in nutrition plays no small part in the matter. Fujii^ ascribes 

 certain changes produced in the cones of a Japanese Pinus after 

 pollarding to over nutrition. Those species of Pinus, already 

 noted, which produce sprouts, do so from the stump after the 

 tree has been cut down, and these sprouts have dimorphic 

 leaves. The same result can be produced in Pinus pondcrosa 

 by cutting off the staminate shoots to which, normally, a large 

 amount of food would pass. This food is diverted by pruning. 

 It is, however, not enough to say this, for there must be some 

 other factors at work. What they are we are not in a position 

 now to say. 



Summary. 



Abnormal leaves are produced upon shoots induced by prun- 

 ing the staminate shoots of Pinus pondcrosa by the hyper- 



^Fujii, K. Bot. Mag., Tokyo, IX, 275-271. 1895. 



