240 STUDIES IN PLANT REGENERATION 
6. If in the shoots of the potato used as cuttings, one bud was 
left uninjured anywhere on the stem, this developed into an aérial 
tuber; if all buds were removed, no shoot-formation took place. 
7. Budless parts of potato tubers were found capable of form- 
ing new shoots on one of the cut surfaces of the nodes. 
8. Regeneration of both kinds of organs occurred at the base 
of the pseudo-bulb of Dendrobium Parishit. 
9. The production of a single root from stems of the seedlings 
of Pimus Laricio and also from one of the older parts shows that 
this kind of regeneration externally resembling а“ restoration ” 
may take place from stems as well as from the apical ends of 
roots. 
10. The majority of leaves used as cuttings regenerated roots 
only; but two new cases were found (Piper canescens) and the 
potato-leaf (Solanum tuberosum) which were able to form a shoot 
and thus reproduce the plant. Тһе roots of such leaves can arise 
either from a callus or directly from the tissue of the petiole. 
Modified leaves such as phyllodes and bulb scales were also able 
to form roots. 
11. Leaves which on the plant have a very short existence 
were found able to prolong this considerably when they formed 
roots. 
12. Regeneration of both kinds of organs occurred in the 
flower stalks of Dudleya californica, and of roots in the inflores- 
cences of Bryophyllum calycinum апа Ruellia rosea. The fruits of 
Phaseolus vulgaris апа Р. lunatus also formed calluses and roots. 
13. The disposition to form roots is much more generalized 
throughout the plant and more easily energized than the power 
to form shoots. Only about one fourth of the parts used produced 
shoots in addition to roots, and only three produced shoots alone. 
This power cannot be explained on structural or teleological 
grounds. 
14. The alga Penicillus capitatus has the power of replacing 
the “head ” of filaments when this is cut off. 
15. Experiments show that regeneration is dependent upon an 
adequate food-supply. In plants from which the reserve food had 
been exhausted by a prolonged exclusion from the light, no 
regeneration took place if the parts were subsequently darkened, 
