1892.] The Difficulties in the Heredity Theory. ; 539 
Blanchard, and others are on the affirmative, or Lamarckian 
side. : 
Physiologists generally have fought shy of the question, 
although I think in the end they will be forced to take it up 
with the morphologists, and give us the physio-morphological 
theory of heredity of the future. Professor Michael Foster of 
Cambridge, and Professor Burdon-Sanderson, of Oxford, both 
write me that the question has hardly come into the physio- 
logical stage of inquiry at all. Yet in England Weismann 
has found his strongest supporters among some of the natur- 
alists: Wallace, Lankester, Thiselton Dyer, Meldola, Poulton, 
Howes, and others; while, excepting Windle, the anatomists, 
including Mivart and Lawson Tait, with Sir William Turner as 
the most prominent, are all Lamarckians. Huxley, Romanes, 
and Flower are said to be doubtful. In this country the 
opinion of naturalists is directly the outgrowth of the class 
of studies in which each happens to be engaged. So far as I 
know every vertebrate and invertebrate paleontologist is a 
Lamarckian,! for in this field all evolution seems to follow the 
lines of inherited use and disuse; most of those engaged upon 
invertebrate zoology incline to follow Weismann. I have con- 
versed upon this subject with many physicians, and find that 
without exception the transmission of acquired characters is 
an accepted fact among the profession. 
Exact Statement of the Problem.—It is important at the 
outset to state most clearly what is and what is not involved 
in this discussion. Weismann’ does not claim that the repro- 
ductive or germ-cells are uninfluenced by habit; on the other 
hand, he admits that most important modifications in these 
cells may and do result from changes of food, climate, from 
healthy or unhealthy conditions of the body; also from 
infectious disease, where it is quite as possible that the 
microbes may enter the reproductive cells as any other cells 
of the body; from alcoholism, where the normal molecular 
action of the protoplasm of the germ-cells may be disturbed, 
-1See the writings of Hyatt, Cope, Ryder, Dall, Scott, and others. 
Essays upon Heredity and Kindred Biological Problems, 1889. Trans. 
