i6o 



INDIVIDUALITY IN ORGANISMS 



inhibited. A part of the stem was then surrounded with 

 water, a, at ordinary temperature to provide the mois- 

 ture necessary for the growth of roots, and roots arose 



on this region. Submer- 

 ging part of the stem in 

 water in this way does not 

 result in the development 

 of roots when the original 

 root system is active. By 

 inclosing a region of the 

 stem in a chamber con- 

 taining ether vapor, and 

 thus anesthetizing but not 

 killing it, McCallum was 

 able to induce the forma- 

 tion of roots above the 

 anesthetized region, as in- 

 dicated in Fig. 93. In this 

 experiment the original 

 root system was present 

 and uninjured, but the re- 

 gion above the anesthe- 

 tized level was apparently 

 cut off from its influence, 

 and, the moisture being 

 sufficient, new roots ap- 

 peared near the basal end. 

 These experiments with roots seem to indicate that 

 not only does a relation of dominance and subordination 

 exist between the different parts of a root system, but 

 that the root system as a whole dominates the stem to a 

 certain extent, so far as the production of roots is con- 



FiGS. 92, 93. — Diagrammatic 

 figures illustrating experiments on 

 root production on the stems of 

 seedlings; only lower parts of 

 plants shown: Fig. 92, formation 

 of roots on stem at a when this 

 region is kept moist after inhibi- 

 tion of original root system, b, by 

 low temperature (after Goebel); 

 Fig. 93, formation of roots above 

 a region of stem inclosed in 

 narcotic atmosphere (after 

 McCallum's description). 



