1905]  Leavitt,— Translocation of Characters in Plants 17 
denotes disturbance of the ordinary physiological factors. In the 
present paper it is not meant to inquire what the nature of this dis- 
turbance is. It is intended to ask only what application teratology 
may have to the problems of evolution. The answer which, in effect, 
has been made is this, that teratological phenomena bring us desired 
information from at least two different sides. In the first place, 
abnormalities have often been held to represent the restoration of 
ancient forms and to reveal the original condition of organs; certain 
abnormalities, in other words, have been regarded as displays of 
atavism. When this is their true nature they show us certain defi- 
nite points which lines of evolution have followed. The remarks of 
Planchon and of Sterns quoted above exemplify this concrete appli- 
cation of the phenomena. Interesting attempts to use teratological 
forms in the interpretation of normal structures, wherein the atavistic 
nature of the occurrences is assumed, are to be found in the con- 
troversies regarding the morphology of the ovuliferous scale of the 
Abietaceae; in discussions of the origin of the Angiospermous ovule ; 
and recently in Dr. Davis's attractive elucidation of the derivation of 
the archegonium.! 
Secondly, abnormality as a general broad phenomenon has, espe- 
cially of late, attracted to itself a strong current of biological thought, 
by reason of its relation to the ideas of “discontinuous variation ” and 
“mutation.” An original, suggestive, and philosophical treatment 
of monstrosity in general, considered broadly as a phase of organic 
development, and in its bearing on evolution, is the work of Casimir 
de Candolle.? He recognizes the parallelism between certain types 
of abnormal deviations and certain demonstrable trends of evolu- 
tionary progress in flowering plants. It is worth while to quote the 
concluding sentences of the essay mentioned. “If teratological vari- 
ations of floral organs have played a róle in past evolution, those 
which have led to present complex forms are to day the rarest, while 
the monstrosities now the most common indicate, in phanerogams at 
least, a tendency toward primitive simplicity of forms. Consequently 
if progressive taxonomic monstrosities of the flower were not in other 
times more frequent and especially more varied than they are to-day, 
they could not have produced, by the sole effect of natural selection,. 
1 Ann. Bot. 17: 477 (1903). 
2 Arch. Sci. Phys. et Nat. Genéve, Mar. 1897. 
AR. 
