202 PLANT HYBRIDIZATION BEFORE MENDEL 



ism, from cell to cell through the pore-canals, makes possible the 

 transfer of stimuli in a manner analogous to that of the nerves, 

 (p. 58.) For transmission to a distant point in the organism, 



". . . there requires to be not merely a single stimulus, but rather a sum 

 of various stimuli to be transmitted, which are able to cause a qualita- 

 tively definite process." 



This sense-image conduction through the idioplasm is conceived 

 of as being brought about by organized albuminous bodies. 



"This theory of dynamic participation appears to me to solve the 

 question at hand in the simplest manner. The idioplasm of all the cells 

 of a plant exists in immediate contact. Every change which it experiences 

 in any place becomes everywhere recognized, and in a corresponding 

 manner utilized. We must assume that the stimulus that operates locally 

 is immediately telegraphed everywhere, and everywhere has the same 

 effect; for everywhere a continuous and general sensation which the 

 idioplasm experiences explains the otherwise impressive fact, that the 

 idioplasm, despite the so dissimilar conditions of nutrition and stimulus 

 to which it is exposed in the different parts of an organism, yet develops 

 and changes everywhere in completely like manner, as we especially 

 recognize from the fact that the cells of the root, the stem, and the leaf, 

 produce exactly the same individual." 



Nageli now constructs a theory of sex development as follows: 

 A peculiar category of Anlagen may occupy a middle place 

 between stability and instability, formed by the cohesion of two 

 or more Anlagen, of which one must develop to the exclusion of 

 the other. This will depend now upon internal and now upon 

 external causes. 



"Thus, doubtless, it is inner, but still unknown causes which, in the 

 case of organisms in which the sexes are separate, determine whether, 

 in a developing embryo, the male or female organism reaches develop- 

 ment." (p. 194.) 



We thus have a purely theoretical conception of sex-equilibrium 

 as existing in the groups of Anlagen in the idioplasm, of which 

 external causes of some sort stimulate the development of some 

 rather than that of their partners in the equilibrium. 



Nageli emphasizes the conception that the increase of the idio- 

 plasm in ontogenetic development takes place 



". . . through the longitudinal growth of the rows, namely, through 

 intercalary insertion of micellae in every micellar row, which thereby 

 elongates, without altering their cross-sectional configuration." (p. 531.) 



Each row, therefore, is considered to contain all the Anlagen 

 which the individual has inherited in the embryo, and each cell 



