1923] 



BEALS — REGENERATIVE PHENOMENA IN PLANTS 373 



THIRD SET OF EXPERIMENTS 



(1) An entire horseradish root was covered with soil. 



(2) A root of the horseradish was peeled down to the pith and 

 covered with soil. 



(3) Horseradish roots were cut in half longitudinally and hori- 

 zontally and were placed in the soil. 



(4) Similar pieces of the sweet-potato were used. 



(5) The peelings of the radish and potato were planted. After 

 one week all pieces, except the peels, exhibited regenerated roots 

 or shoots. As previously described, these parts were removed, 

 fixed, and preserved for study. 



(6) Four detached Bryophyllum leaves were placed in a moist 

 chamber on wet sand with the bases of the petioles covered. 

 Every notch exhibited regenerated shoots and roots. The 

 earliest stages of these were cut off and killed. 



Perhaps the most interesting regeneration was developed by 

 the flax seedlings. The flax seeds were repeatedly planted in 

 porous saucers containing a mixture of sand and soil, and kept in 

 moist chambers. After the unfolding of the cotyledons, these 

 seedlings were decapitated about 1-2 cm. beneath the cotyledons. 

 In some instances where the roots were above the soil, these too 

 were cut off. After 6 to 10 days, each stem exhibited tiny swell- 

 ings, as many as 8 appearing on one stem. Soon these swellings 

 developed into shoots. When the root was cut off, these swell- 

 ings appeared at the base of the stem and soon developed into 

 new roots. As many as 4 regenerated roots developed on one 

 plant. The stems that exhibited swellings and regenerated roots 

 and shoots were cut into small sections so that each section had 

 one swelling or regenerated root or shoot. These sections were 

 then fixed as described below. 



After washing, the materials were dehydrated, infiltrated, 

 sectioned, and mounted in balsam according to the method given 

 in Chamberlain's ' Methods in Plant Histology. ' Some of the 

 sections were stained in Delafield's haematoxylin and some in 

 saffranin. 



As stated before, after some regeneration was evident with 

 the hand lenses, those sections and those giving slight indication 

 of the possibility of regeneration as described before were killed 

 with the following solutions: 



