XXXI 
ON THE TRANSFORMATION AND REGENERATION OF 
ORGANS! 
I 
SEVERAL of the older scientists, for instance, Bonnet, 
Spallanzani, and Dalyell had occasionally observed that in 
the place of a head a tail may be regenerated in lower 
animals.” These casual observations had been considered as 
curiosities or pathological cases, and scientists took no further 
notice of them. It occurred to me that it might be possible 
to produce the substitution of one organ for another at 
desire, and that in this way we might gain an insight into 
the physiology of morphological processes. Having tried 
in vain to accomplish this result during the year 1888 in 
Kiel, I succeeded the following year at Naples. I found 
that if the foot of a Tubularian be cut off and the foot 
end of the stem surrounded on all sides by sea-water a head 
will be produced instead of a foot, while the same end 
produces a foot if it is in contact with some solid body, 
like the bottom of the aquarium: This arbitrary substitu- 
tion of one organ by another I called heteromorphosis in 
contradistinction to the case of regeneration in which the 
same organ is reproduced. I succeeded in showing that 
phenomena of heteromorphosis can easily be produced in all 
kinds of Hydroids and in Tunicates.’ 
Since then a great number of heteromorphoses in various 
classes of animals have been obtained. The most brilliant 
accomplishment in this field of science is undoutedly 
Herbst’s discovery that if in Crustaceans the eye together 
1 American Journal of Physiology, Vol. IV (1900), p. 60. 
2Part I, p.115. 3 Loc. cit. 
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