REMARKS 
UFON A STATEMENT PUT FORTH BY PROFESSOR VALENTIN, 
RESPECTING PREVIOUS RESEARCHES ON THE SUBJECT OF 
THIS WORK. 
Arter I had finished this Treatise, I received the first part 
of Wagner’s ‘Lehrbuch der Physiologie! Leipzig, 1839; 
which was just then issuing from the press, and which con- 
tained (at page 182) an outline of the development of the 
animal tissues, communicated by Professor Valentm. The 
author introduces the subject with some historical remarks, 
in which he represents my researches as giving an essen- 
tial completeness to the analogies between animal tissues 
and vegetable cells which had been previously pointed out, 
more particularly by himself. There are very many ways 
of drawing a comparison between two objects, and simi- 
litudes may be discovered which are opposed to the whole 
internal construction of the things in which they are observed. 
Everything, therefore, depends upon the sort of comparison 
drawn. If Valentin’s historical representation be justified, the 
idea of a comparison, similar in its kind to that on which my 
researches are based, must have a previous existence in his 
earlier investigations. I have endeavoured to analyse the 
fundamental idea of my investigation in the commencement 
of the Third Section of this treatise ; it was this—that one 
common principle of development forms the basis of all the 
elementary particles of organisms. It origmated in a com- 
parison being drawn between a cartilage-cell and a vegetable 
cell, in such sense, that the molecules are united together for 
the formation of both of them, in accordance with similar laws, 
since in both instances a nucleolus is first fermed ; around this 
’ Rudolph Wagner’s Elements of Physiology, translated by R. Willis, M.p., p. 214. 
