80 THE MICHIGAN ACADEMY OF SCIENCE. 



REGENERATION OF THE EPICOTYL IN SEEDLINGS OF VICIA 



FABA AND PISUM SATIVUM. 



ARABEL W. CLARK. 



( Abstract. ) 



Cotyledous were first plauted with a small piece of the epicotyl left 

 attached, and it was found that a whole plant was regenerated. This 

 regeneration took place, whether a whole cotyledon or only a small piece 

 of a cotyledon was left intact, thus indicating that regeneration is not 

 dependent upon the food-supply. 



When an epicotyl was injured or removed, first the six buds which had 

 been laid down in normal growth, developed into shoots, and by remov- 

 ing each newly regenerated shoot as it appeared, the seedlings were 

 forced to send out from six to sixteen shoots successively. These shoots 

 continued to appear until all the embryonic tissue was dead. 



Until the epicotyl had reached a height of ten cms., the age of the tis- 

 sue operated on, seemed to have little influence on the time required for 

 regeneration; at fifteen to thirty degrees C, regeneration took place in 

 from six to seven days after the epicotyl and side buds had been removed. 

 After the epicotyl had reached a height of ten cms., regeneration was 

 not so certain, and at twenty cms. only an occasional seedling regener- 

 ated, although the cotyledons were found to be rich in food-supply. 

 When the epicotyl was cut off above the first node, a shoot was sent out 

 at the node and the side buds did not develop. Regeneration in the 

 epicotyls of Vicia faba and Pisum sativum is apparently more depend- 

 ent upon the age of the tissue operated on, than upon the amount of 

 food-supply at hand. 

 Arabel W. Olark^ 



Botanical Laboratory, University of Michigan, 

 Ann Arbor. 



THE ANGLE OF DEVIATION FROM THE NORMAL POSITION 



AT WHICH STEMS SHOW THE STRONGEST 



GEOTROPIC RESPONSE. 



JULIA ANNA HAYNES. 



(Abstract.) 



The experiments of Sachs, Darwin and Bateson, and Stone have shown 

 that in the seedling-roots, flower-stalks, and grass-nodes used by them, 

 the strongest geotropic response was made for a deviation of 90 

 degrees from the normal position of those organs. Czapek, and Darwin 



