178 . Recent Literature. | ZOE 
the topic, The Limits of Reversion, the author calls attention to 
the fact that an abnormal organ or structure, even though it re- 
sembles some normal structure in a lower animal, is not necessarily 
a reversion, but may be a coincidence. | 
There is danger of forgetting the branching plan of evolution and 
jumping to the conclusion of a connection where none exists. In 
concluding, Dr. Osborn says: ‘‘ There are clearly marked out sev- 
eral regions in-the human body in which evolution is relatively most 
rapid, such as the lower portion of the chest, the upper cervicals, 
the shoulder girdle in its relation to the trunk, the lower portion of 
the arm and hand, the outer portion of the foot. We notice that 
these regions especially are centers of adaptation to new habits of 
life, in which new organs and new relations of parts are being ac- 
quired and old organs abandoned. 
We observe, also, that all parts of the body are not equally 
variable, but these centers of evolution are also the chief centers of 
variability. The variations here are not exclusively, but mainly, of 
one kind; they rise from the constant struggle between adaptation 
and the force of heredity.’’ CAR: 
The Difficulties in the Heredity T) heory. By HENRY FAIRFIELD 
OsBporn.* In the second Cartwright Lecture for 1892, Dr. Osborn 
discusses the bearing of the facts of human evolution enunciated in 
his previous lecture upon the inheritance of acquired characters. 
The generalizations in this paper are, for the most part, re-state- 
ments of his views upon this subject, in some cases from new points 
of view. 
The history of the heredity theory is briefly outlined, and the 
effect of impacts and strains upon the mammalian foot and the 
wearing of cusps is again alluded to. The article concludes with 
some brief remarks on the inheritance of mutilations, the effects of 
previous fertilization, and maternal impressions. The author is in- 
clined to believe in all three, and especially declares his acceptance 
of the influence of maternal impressions upon the young. The 
note upon the inheritance of mutilations of the tails of mice is of 
interest, but, as the author remarks, would need confirmation. 
CsA. 
* The Am. Nat. xxvi, 537-507. 
