264 BOTANICAL GAZETTE [MARCH 
The conclusions are that “the radial structure of the seed, the short free 
apical portion of the nucellus, the presence of a pollen chamber, the extension 
of the bundle system into the free portion of the inner integument, the complex 
structure of the outer integument, are all points of contrast with sl jaeoacae 
and probably indicate the more primitive nature of the Gnetum ovule. 
Resemblances to Bennettites are also pointed out, and the general impression 
is left that Gnetum, Welwitschia, Bennettites, and Lagenostoma, on the basis of 
ovule structure, are all from some common ancestral stock.—J. M. C. 
Annual ring and medullary rays of Quercus.—Groom® has investi- 
gated the evolution of the annual ring and medullary rays of the oak, using 
numerous and widely distributed species, and has reached the following con- 
clusions. The very distinct annual rings of the deciduous species become less 
marked in evergreen species, but may be recognized by certain structural 
features that are enumerated, any one or more of which may be lacking. 
There is an interesting correspondence between the habit and the arrange- 
ment of the large vessels in the annual ring. “Species showing the most 
striking pore-zone are deciduous; those showing it regularly and distinctly, 
but not having so marked a disproportion in size between the innermost and 
outermost vessels, are subevergreen; whilst those species with no trace of a 
transitional forms with corresponding transitions in the pore-zone display. 
All species were found to possess uniseriate shallow medullary rays, and 
some possess also broad, high multiseriate rays; and there are numerous transi- 
tional stages between these two kinds of rays. The author was not able to 
decide which type was primitive, the evidence being contradictory as yet. 
There are cases, as in seedlings of Quercus and Alnus (BAILEY and Eames), in 
which narrow rays form broad ones; other cases, as in Fagus (Jost), in which 
broad rays divide into smaller ones; and still other cases, as in seedlings of 
Fagus (Tasor), in which both kinds of changes go on simultaneously in the 
rays of the same annual ring.—J. M. C. 
parasites of Nepenthes.—An interesting case of symbiosis, 
somewhat analogous to the presence of intestinal parasites in animals, has been 
reported by JENSEN.” The pitchers of Nepenthes have long been known to be 
partially filled with a fluid containing enzymes in which dead insects seem to 
be digested, but only with the observations of the present author has attention 
been directed to the fact that several species of dipterous larvae appear to 
develop normally in this fluid. So abundant are they that JENSEN declares 
that of the hundreds of pitchers he has examined from year to year at Tjibodas, 
8 Groom, Percy, The evolution of the ovens ring and medullary rays of Quercus. 
Ann. Botany 25:983-1003. pls. 74-76. 19 
19 JENSEN, HJALMAR, Nepahe Ter. II. Spee Notizen. Ann. Jard. 
Bot. Buitenzorg Suppl. 3. pt. 2. 941-946. 
