80 BOTANICAL GAZETTE 7 [JANUARY 
the combination of numerous independent size factors is criticized by GATES® 
(1) on the basis of cytological evidence (tetraploid chromosomes) to the con- 
trary, and (2) on the basis of their sudden, discontinuous origin.—R. A. 
EMERSON. 
Araucarians.—Miss Ho.pEn’ has recently described the stems of two fossil 
plants from eastern Canada, a Tylodendron from the south shore of Prince 
Edward Island and a form which she claims is Voltzia coburgensis from the 
Triassic at Martin’s Head, New Brunswick. She has identified her specimens 
by the casts of the pith, and by the structure as well, and uses her determina- 
tions as evidence of the geological horizon of the strata in which they are found. 
In this connection, she states: ‘‘Since Tylodendron is characteristic of the Per- 
mian, there can & no question that these strata [those of Prince Edward Island] 
are of that age”; and of Volizia: ‘“‘Paleobotanical evidence indicates that the 
Mesozoic strata of New Brunswick are of the same age as those of the eastern 
United States, and should be correlated with the Lettenkohle or Lower Keuper 
of Europe.” The pith casts of her Tylodendron are typical, and she states of 
the ligneous structure: “It agrees exactly with that described by Dawson 
from Mr. Batn’s specimen as Tylodendron cyte and with that described by 
POTONIE as sash apes cca een pionconens Goepp 
In discussing t} 1 against te generally accepted view of the 
araucarian affinity of Tylodendron, a view, however, from which Miss HOLDEN 
dissents, she agrees with Poronré that ‘“‘the nodal swellings and instanding 
protoxylem strands causing the ridges and furrows of the pith casts are identical 
with similar structures in Araucaria and Agathis,’”’ but states that instanding 
protoxylem strands are common to all living conifers. She admits that the 
medullary rays are typically araucarian, the rays uniseriate, rarely over 10 
cells high, and composed of thin-walled cells, but she says that all conifers have 
uniseriate rays. Neither of her arguments, however, precludes the araucarian 
connection. Of the tracheary pitting, she says: ‘Its closely compressed and 
alternating pits clearly affiliate it with Araucarioxylon Krauss,’’ but she consid- 
ers that this does not indicate araucarian affinity, since ‘closely compressed and 
alternating pitting is not the primitive condition for the Araucarineae.” This 
statement is made on the authority of Professor JeFFREY’s® recent work, While 
both of these articles were in press, however, the writer? advanced evidence 
Gates, R. R., poate mutants and chromosome mechanisms. _ Biol. 
Centralbl. pe 92-99, 113-150. 
7 HoLpEN, Miss R., Some aa plants from eastern Canada. Ann. Botany 27: 
243-255. 1913. 
8 Jerrrey, E. C., The history, comparative anatomy, and evolution of the Arau- 
carioxylon type. Proc. Amer. Acad. 48:531-571. 1912. 
® THomson, R. B., On the comparative anatomy and affinities of the Araucarineae. 
Phil. Trans. Roy. Soc. B 204:1-50. 1913. 
