A CHRISTENSEN BIBLIOGRAPHY 9 
It may be added that, in the opinion of the writer, 
such variations are teratological in their nature. As 
such, they may be of great significance in the study of 
the nature and development of plant organs, but have 
little meaning for purposes of classification and should 
not be given separate names. 
The accompanying illustration, kindly made for the 
JOURNAL by Miss Una L. Foster, shows a very full 
series of gradations between normal fertile and sterile 
fronds. 
Conk w: 
Several weeks ago I received from Miss Sarah F. 
Sanborn, of Concord, N. H., a number of fertile fronds 
of the Ostrich Fern which were partially developed as 
foliage fronds after the manner of the obtusilobata form 
of the Sensitive Fern. In regard to these, Miss Sanborn 
writes: ‘‘My Ostrich Ferns have grown for years on the 
east side of my house, but I never before saw such 
abnormal growths. I am inclined to think that the 
great quantity of wood ashes I used about the ferns 
had the effect noticed.” 
Here seems to be another bit of evidence in line with 
the above discussion. Have any of our readers further 
evidence bearing on the matter? If so, they are invited 
to send it in to the editors. 
KJ. W. 
A Christensen Bibliography 
Some time ago a list-of the botanical writings of Mr. 
Carl Christensen was published in the Journau.'’ He 
has now sent us the following list, complete up to the 
end of 1914. It has already been printed, partly in his 
own work on Danish botanical literature, partly in the 
12: 56. 1912. 
