36 o y e ff re y and Cole. — Experimental Investigations 
Abietineae but are not normally present in the rays of this genus. Later, 
Miss Holden 1 made clear that the possibility of the recall of marginal 
tracheides was widespread in both the Taxodineae and Cupressineae. 
Professor W. P. Thompson 2 has demonstrated a similar situation in the 
genus Abies among the higher Abietineae, where, as a consequence of 
injury and especially in the root, ray tracheides make their appearance. 
Recently 3 it has been shown that in the existing araucarian Conifers the 
parenchymatous elements found as a normal feature of organization of the 
wood of many Mesozoic Araucarioxyla may be recalled by experimental 
means. This situation is none the less significant because the presence of 
wood parenchyma is a normal feature of organization of the conservative 
parts of the living representatives of the Araucarineae. 
It will be clear from the summary statement made in the last 
paragraph that experimental methods have been of great value in the 
study of the evolutionary history of the coniferous Gymnosperms. In the 
case of the Angiosperms the fossil record is at the present time extremely 
incomplete so far as structural remains are concerned ; and the study of 
existing forms by experimental procedure is as a consequence of even 
greater importance relatively than it is in the Conifers. In the present 
communication it is proposed to show the value of the study of abnormal 
material in the case of the non-vascular magnoliaceous genus Drirnys. The 
absence of vessels in this interesting genus of the Southern Hemisphere was 
noticed in the early forties of the last century by Goeppert (Goeppert, 
Linnaea, 1 6. 1842). This condition is of particular interest in view of the 
speculations in regard to the origin of the Angiosperms, which in the case 
of certain investigators have been made to centre around the Magnoliaceae. 
The floral organization of the Magnoliaceae and related families has been 
the main point of argument in this connexion. Obviously it is well to 
consider possible evidence of the primitive character of the group from 
anatomical characteristics. Clearly the absence of vessels, if an original 
condition in the Magnoliaceae, would furnish a strong indication in this 
direction, were the gymnospermous forms hypothetically antecedent to the 
Angiosperms themselves non-vascular. If the Gnetales are ancestral to 
the Dicotyledons, as has been suggested by Arber and Parkin 4 as well as 
other investigators, evidently the absence of vessels in any angiospermous 
1 Holden, Ruth : Ray Tracheides in the Coniferales. Bot. Gaz., vol. lv, No. i, Jan. 1913, 
Pis. I and II. 
2 Thompson, W. P. : Ray Tracheides in Abies. Bot. Gaz., vol. liii, 1912, pp. 331-8, 
Pis. XXIV, XXV. 
3 Jeffrey, E. C. : The History, Comparative Anatomy, and Evolution of the Araucarioxylon 
Type. Part I. Proceedings of the American Academy of Arts and Sciences. Vol. xlviii, No. 13, 
Nov. 1912. 
4 Arber, E. A. Newell, and Parkin, John : On the Origin of Angiosperms. Journ. Linn. Soc., 
London, Bot., vol. xxxviii, 1907, pp. 29-80, 
