[From the Buttetin oF THE TORREY BorTanicar Ciup, 33: 67-76, A2. 4, 5. 1906. | 
Studies in etiolation 
AUGUSTINE DAWSON SELBY 
(WITH PLATES 4 AND 5) 
During the winter of 1902-1903 the writer carried on certain 
Studies of the effects of etiolation upon several species of plants 
in the laboratories of the New York Botanical Garden. Most of 
the species studied were latex-bearing sorts. Owing to the press 
of regular duties, and to ill health, the publication of the results 
has been long delayed —far too long, indeed. It seems, how- 
ever, worth while to present them briefly at this time. An an- 
nouncement of the results obtained with Persea was made before 
the Botanical Society of America at its Washington meeting, 
January 1, 1903. 
Seedlings of the Alligator pear (Persea gratissima) were grown 
in a dark room and propagating houses of the Garden, toward the 
end of 1902. At the end of ten weeks the normal and etiolated 
plantlets had developed stems approximately equal in length 
(about 45 centimeters) which consisted of 17 and 19 internodes 
respectively (plate 4, figure 7). The variation in the length of 
the internodes of the normal plantlets was slightly greater than 
with the etiolated. No acceleration was shown in rate of growth 
by the etiolated plants, nor was the total amount of growth greater 
ian in the normal. The stem-diameters were nearly the same in 
both cases. All the leaves of the etiolated stems were bract-like 
and rudimentary (plate 4, figures 3 and 4); these did not advance 
beyond a certain stage of 10 mm. in length, with blades 5x 2 mm., 
when they withered and dropped off. These rudiments seem gen- 
erally comparable with the rudimentary organs borne on the basal 
67 
