362 Notes on Recent Literature. 
Medullary Rays and the Evolution of the 
Herbaceous Habit. 
1. A. J. Eames : “ On the Origin of the Broad Ray in Quevcus .” Bot. 
Gaz. XLIX., March, 1910. 
2. I. W. Bailey: “Reversionary Characters of Traumatic Oak Wood.” 
Bot. Gaz. L., November, 1910. 
3. Ibid : “ The Relation of the Leaf-trace to the Formation of Compound 
Rays in the Lower Dicotyledons.” Ann. of Bot. XXV., January, 1911. 
4. A. J. Eames : “ On the Origin of the Herbaceous Type in the Angio- 
sperms.” Ann. of Bot. XXV., January, 1911. 
5. W. P. Thompson: “On the Origin of the Multiseriate Ray of the 
Dicotyledons.” Ann. of Bot. XXV., October, 1911. 
6. Percy Groom : “ The Evolution of the Annual Ring and Medullary 
Rays of Quevcus." Ann. of Bot. XXV., October, 1911. 
mHE series of papers whose titles are given above, embody the 
L results of an interesting and important series of researches 
into the structure and phylogenetic connexions of the different types 
of medullary ray occurring in dicotyledons, and of the relation of 
ray-formation to the evolution of the herbaceous habit among 
Angiosperms. They all (except the last) emanate from the Phanero¬ 
gamic laboratories of Harvard, where the work was carried out 
under the general direction of Professor Jeffrey. 
The aggregation of a number of closely approximated uniseriate 
rays in certain longitudinal hands of the secondary xylem occurs in 
a number of Cupuliferae, and to these the name “ false ray ” has 
sometimes been applied. The occurrence of these “ false rays ” in 
the wood of a Miocene Oak led Eames (1) to investigate their 
relation to the typical broad multiseriate rays of modern oaks. It was 
found that several tertiary oaks had rays of this kind and that the same 
condition was demonstrable in the seedlings of several existing black 
or red oaks ( Erythrobnlanus). In the seedlings of the white oaks 
(Lepulobalanus) the uniseriate type of ray alone exists ; while in 
the later formed wood of these seedlings, as in the earliest wood of 
“ black ” oaks and in the twigs of adult “ live ” (evergreen) oaks, 
various stages of the “ compounding ” of these uniseriate rays occur. 
In this process of fusion of the uniseriate rays, fibres and wood- 
parenchyma-cells are often included in the compound ray. Even¬ 
tually we come to the typical broad homogeneous rays of the adult 
deciduous oaks, which clearly form the term of this series of condi¬ 
tions. It seems difficult to read the series as other than pro¬ 
gressive, so that we may conclude that the broad ray of the modern 
deciduous oaks is a compound structure orginally derived in descent 
from the fusion of a number of uniseriate rays. Numerous uni¬ 
seriate rays co-exist, of course, with the compound rays in the wood 
of the modern oaks. 
An interesting confirmation of this conclusion was found by 
Bailey (2) in wounded oakwood. The secondary wood formed 
immediately external to the seats of wounding contained only uni¬ 
seriate rays, but in the later formed wood all stages of the com¬ 
pounding of these to form broad rays were met with. Jeffrey has 
given good ground for believing that in several instances traumatic 
areas of tissue show reversionary characters, and the evidence of 
the wood formed after wounding in oaks thus supports the theory 
of compounding based on palaeontological and ontogenetic evidence. 
In a second paper (3) Bailey discusses the cause of the aggre¬ 
gation of ray-tissue along certain radii which is found in the formation 
of broad as opposed to narrow rays. He extends Eames’ results to 
