210 BENEDICT: NEW VARIETIES OF NEPHROLEPIS 
The conclusions reached by the writers specified above are like 
those of any similar morphologic or systematic research, but differ 
in the use of the term “‘orthogenesis,”’ instead of ‘tendency to 
vary,” “trends of variation,” or some similar expression. This dif- 
ference is of interest, however, because it lays emphasis on the belief 
that the evolution of the present-day organic world has not been 
by chance fluctuation, but has proceeded in an orderly fashion in a 
law-conforming way. According to orthogenetic theory, evolu- 
tion proceeds, at least in part, by the progressive intensification of 
characters in any series of forms, regardless of considerations of 
adaptation or utility. In the long run, of course, only such forms 
as possess useful characters will survive. 
In the present case, the lines of variation do not appear to be 
in the jnterests of utility. The new forms produced are not as 
adaptable to natural conditions as the original species from which 
they all originated. Proof of this is found in the fact that the va- 
rious new varieties are, in general, more difficult of cultivation than 
the original form, and further proof is contained in the fact that none 
of the varieties of N. exaltata bostoniensis have been found wild 
in the tropics. It may appear then that these fern varieties, pro- 
duced so artificially and unnaturally, are poor forms to cite as illus- 
trations of orthogenesis. This would be true were it not for the 
fact that the same types of variation appear everywhere among 
ferns as distinctive of recognized species or even genera. That 
is, fern species have differentiated naturally by the same mannet 
and degree of variation as is shown by these horticultural varieties. 
On this basis, these Boston fern sports may be considered as un- 
successful variations, either premature or normal, perhaps called 
forth or at least perpetuated by the unusual cultural conditions. 
Like wild forms in other genera in the degree of their variation, 
they are unlike them in having developed no means of maintaining 
themselves under natural conditions, and if put to the test fe) 
competition, would soon be disposed of by natural selection. 
They may be said to indicate potentialities of variation in Nephro- 
lepis. It is worth while noting that variations of similar tyPé 
but of spore origin, have appeared in other fern genera, notably 
Polypodium and Polystichum. 
