Marcu 15, 1912] 
the teaching staff and graduates. The prin- 
cipal article in the first number will be an il- 
lustrated paper on “ Architectural Acoustics ” 
by Professor W. C. Sabine, with a practical 
discussion of a number of recent theaters, lec- 
ture halls and churches. The number will also 
contain several drawings of important ex- 
amples of European architecture and an essay 
on “The Medieval Town Halls of Italy” by 
H. E. Warren, S.M. in Architecture, 1905. 
Early numbers of the Quarterly will contain 
examples of recent work in architectural de- 
sign by students of the school, a paper on 
professional practise, the substance of three 
lectures recently delivered before the school 
by Mr. Cass Gilbert, of New York (lately presi- 
dent of the American Institute of Architects), 
and papers on the teaching of architectural 
design by Professor Duquesne, on the study of 
architectural history in its relation to the pro- 
fessional study of architecture by Professor 
H. L. Warren, and further papers on acoustics 
by Professor Sabine. 
THE PRESENT KNOWN DISTRIBUTION OF 
THE CHESTNUT BARK DISEASE. 
THE writers published in Farmers’ Bulletin 
467, page 6 (issued October 28, 1911), a map 
showing the distribution of the chestnut bark 
disease as known in June, 1911. Since that 
time the disease has spread considerably, also 
our detailed knowledge of its distribution has 
increased. In the map here published, thin 
horizontal lines show the general distribution 
of uninfected Castanea dentata. Thick lines 
variously arranged in concentric bands indi- 
cate general regions of gradually increasing 
infection which culminate in the region of 
practically complete destruction of the tree 
about New York City. Black dots represent 
the location of advance infections, many of 
which have already been eradicated. The 
writers are under obligations to Dr. Perley 
Spaulding, Professor A. H. Graves, Mr. I. C. 
Williams, Mr. S. B. Detwiler and the mem- 
bers and employees of the Chestnut Tree 
Blight Commission of Pennsylvania, Mr. W. 
H. Rankin, Mr. J. F. O'Byrne, Mr. F. W. 
Besley, Dr. Ernest S. Reynolds, Mr. H. G. 
SCIENCE 
421 
MacMillan, Professor H. R. Fulton and Mr. 
A. B. Brooks, for much of the data used in 
compiling this map. 
Haven Mercarr, 
J. Franxiin CoL.ins 
OFFICE OF ForEsST PATHOLOGY, 
BUREAU OF PLANT INDUSTRY, 
WASHINGTON, D. C., February 1, 1912 
SPECIAL ARTICLES 
SENILITY IN MERISTEMATIC TISSUE 
MeristEeMaTic tissue in perennial plants is 
commonly believed to retain its embryonic 
condition unchanged. Senility is considered 
to occur only in specialized cells. A twig cut 
from a mature tree and planted or grafted is 
said to produce a new tree as youthful in its 
protoplasmic vigor as a seedling. While these 
are almost the unanimous opinions of the 
botanists, it is interesting to note that many 
fruit growers and gardeners have always held 
that vegetatively propagated plants tended to 
run out, as if through senility. 
In order to determine, if possible, which of 
these views is better justified, a series of in- 
vestigations on meristematic tissue in peren- 
nials of different ages have been carried out, 
and this article is a brief preliminary state- 
ment of one of the more obvious results. 
The structure of the adult leaves gives 
valuable insight into the meristematic tissue, 
since any minute changes occurring in the 
latter will be made larger and more obvious in 
the leaves, just as the inherent characteristics 
of seeds become more apparent in the plants 
into which they grow. If, therefore, the meris- 
tematic tissue of a perennial is changing with 
the increasing age of the plant, the new leaves 
appearing each year should reveal differences. 
In order to eliminate differences due to ex- 
ternal factors, leaves were taken from cuttings 
of Vitis riparia of different ages grown under 
identical conditions. Comparisons were also 
made between leaves borne by vines growing 
wild, side by side under apparently identical 
conditions, and on many other kinds of trees 
and vines. 
An interesting condition in the venation of 
the compared leaves was one of the results 
