68 
The collection has been maintained in much diminished size 
during recent years. It is still, however, well representative of 
1 
— 
the variation of this fern genus, and constitutes a collection whic 
could not be duplicated in any institution. 
Colchicine Experiments 
These Nephrolepis variations present many unsolved researeh 
problems, in comparative anatomy and cytology, for example. Dur- 
ing the past two years one specific line of research was prosecuted 
at the suggestion of and with the help of Dr. A. F. Blakeslee, of 
the Station for Experimental Evolution at Cold Spring Harbor, 
Long Island; namely, the possibility of inducing variation through 
colchicine treatment. Two lines of experiment with colchicine 
were carried on here at the Botanic Garden. Vegetative parts of 
the plants, particularly the stolons, were immersed in colchicine 
solutions of different strength, following the procedure successfully 
carried out at Cold Spring Harbor with flowering plants. The 
results, at first promising of positive variation, were finally nega- 
tive. The fern tissues became considerably swollen but did not 
reproduce new plants, and histological examination by Dr. Satina, 
at Cold Spring Harbor, indicated that the swelling was pathologi- 
cal. In a second series of experiments, carried on at Brooklyn 
College with the help of Miss Theresa Rosenberg, fern spores 
were treated with colchicine and their germination watched. Ger- 
mination of the spores was obtained, and prothallia consisting of 
a very few large cells resulted, but no later stages developed. The 
chicine results, 
— 
ay 
enlarged cell size is one of the indicia of positive co 
but, so far, none of the treated material has lived long enough for 
any certain determination, 
Fern Familics and Species 
The fern collections of the Botanic Garden over a period of 
twenty-five years have been given some recognition not only for 
special study in variation in Nephrolepis, but also as a general rep- 
resentative collection of significant fern families and species, and in 
relation to the horticultural use of ferns. At the present time, 
the general fern collection, small as it is in comparison with some 
of the earlier greenhouse collections in this country and Europe, 
