212 STUDIES IN PLANT REGENERATION 
recently discussed by Vochting,* Gager, t and others; and finally 
no better illustration could be cited of the difference in the reactions 
of parts possessing buds and parts deprived of them. 
Regeneration in budless parts of potato-tubers was carefully 
worked out by Rechinger.§ He succeeded in inducing the forma- 
tion of a shoot from cubes 4 cm. in diameter cut from the center 
of the tuber. He traced the origin of the scanty callus formed to 
the cambial strands which ramify through the stem, and showed 
that the shoot always arose in the neighborhood of such a callus. 
When he removed the “ eyes ” of the potato and cut the remainder 
into halves or quarters, shoots formed on the cut surfaces. Some 
experiments performed before the writer had learned of Rechinger's 
work may be worth mentioning, as they showed some slight dif- 
ferences from his results. 
Experiment 23. — From a series of potatoes, the buds, together 
with approximately 1 cm. of underlying tissue were removed. 
After a period varying considerably on the different occasions on 
which the experiment was performed, buds appeared on one of 
the surfaces exposed by cutting out the original buds. Тһе “ re- 
action-time " in these cases varied from thirty-six days to five 
months, and one potato lived fourteen months without regener- 
ating or decaying. This variation was independent of the season 
of the year, as was proved by the fact that great differences were 
observed in similar seasons of recurring years. Nor was it slowest 
in the fall and quickest in February, as might have been expected 
from the normal sprouting habits of uninjured potatoes. The 
differences were doubtless due to the fact that no one variety of 
potatoes could be secured for all the experiments, and that no 
definite information could be obtained as to the names of the 
varieties purchased. 
* Vochting, Н. Uber die Keimung der Kartoffelknollen, Bot, Zeit. бо: 86. 
1902. 
t Gager, C. S. Tuber-formation in Solanum tuberosum in daylight. Torreya 6: 
181. 190 
i Knight (Phil. Trans. 1806) found that when the tubers were pinched off from 
the lower nodes, as they appeared on the plant, these were formed above ground, in 
the light. As far as I know, however, the behavior of cuttings in this respect has not 
before been recorded. 
1 Rechinger, С. Verh. zool.-bot. Ges. Wien 43: 315. 1893. 
