BRIEFER ARTICLES. 
TOLERANCE OF DROUGHT BY NEAPOLITAN CLIFF FLORA. 
(WITH THREE FIGURES) 
Tae writer has already made mention of several of the most abundant 
_ Species on the cliffs in the vicinity of Naples.t Some of these plants seemed 
to offer sufficient points of interest to be worthy of more detailed study, 
and a few notes in regard to their summer condition are here offered. 
At Pozzuoli, where most of these observations were made, the strip of 
fertile soil which skirts the beach is bounded on the landward side by 
diffs, in many places quite vertical, rising to a height of thirty to more 
than a hundred meters. These cliffs are occasionally of trachyte, but 
most frequently of gray or yellowish tufa, which in softness and porosity 
closely resembles the softest brick used in interior construction by American 
ilders. Decomposed it makes a moderately rich and very warm soil. 
The chemical composition of two such tufas (from the little island of 
Vivara, 8.3 miles (13*™) from Pozzuoli, of the same volcanic series and 
Not greatly different age from the Pozzuoli deposits) is as follows: 
Gray Tufa Yellow Tufa 
MS ie 51.08 45-50 
(AG PRN te ec oc T3.7t 16.05 
} PS Be ee igs 8 13.16 11.69 
q Mie eres 4.72 gs 20 
WO ae 7. 5.03 
q2 , AO eee ree ee 2.04 2.28 
K,0 Fie at erg Og ae eee a5 2.04 4.12 
Pe oe 4.58 9. 36 
Ris eid atees tle ee 1.50 
RE re ie tse ibs hue oe een 0.40 
JOO. 22 99-13 
___On account of the porosity and the vertical extent of these tufas, the 
) Soil water sinks to great depths, springs (except profound volcanic — 
_ “f€ unknown, and the southerly faces of the cliffs during the summer 
_ Months appear perfectly dry. 
July August 
Mean daily temperature,°C. . . . 24-14 sqe 
Mean precipitation,mm. . . - - 19:12 ae 
: *Bor. Gazerre 35: 360-362. 1903. : 
had) 
449 
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