PLANT HYBRIDIZATION BEFORE MENDEL 201 



The ontogenetic development of the individual begins, during 

 which time the micellar rows in the idioplasm which cause the 

 first developmental stage become active. This induces a passive 

 growth of the other rows, and an increase, perhaps manifold, of 

 the entire idioplasm. A tension arises from inequality in the 

 growth-intensities of the different rows, which sooner or later, 

 according to the number, arrangement, and energy of the active 

 rows, brings the process to a standstill ; the tension is felt as a 

 stimulus due to disturbance of equilibrium, and this tension is 

 shifted from one group of Anlagen to another, until all are passed 

 through, and the ontogenetic development arrives again at the 

 original embryonal state, during the reproductive period, (p. 40.) 



The effect of nutrition upon the idioplasm is interpreted by 

 Nageli as follows : 



The nutritional, stimuli, generally speaking, although they do 

 not alter the idioplasm qualitatively, may still affect the develop- 

 ment of the Anlagen, so that Anlagen which might otherwise re- 

 main latent now come into development, or, the nutrition being 

 lacking, their development is checked. 



Nageli considers it possible that the idioplasm may only return 

 approximately, during the reproduction stage, to its original con- 

 stitution, and that a slow phylogenetic metamorphosis may take 

 place, fp. 53.) It is manifest, as he says, that, in order for this 

 to occur, the external influences must either directly or indirectly 

 bring about a metamorphosis of the idioplasm, (p. 54.) In order 

 for the idioplasm undergoing change in some specific part of the 

 organism to bring about alterations in the rest, the result must 

 be achieved in either a material or a dynamic way. By the former 

 method, Nageli conceives it possible that all the cells communi- 

 cate with one another and with the nearest sieve tubes by means 

 of very fine pores. 



"The sieve-tubes, however, which represent large canals with laterally- 

 large openings in the uninterrupted partition-walls, bring about the ex- 

 change between the most different and distant organs." (p. 56.) 



According to the dynamic theory, if all plant cells communi- 

 cated with one another through fine pores, then these pores con- 

 tain, besides the trophoplasm, also idioplasm, "so that the latter 

 forms a connecting system through the whole organism." The 

 net-like connection then of the idioplasm throughout the organ- 



