TENOPYR: CONSTANCY OF CELL SHAPE 75 
each type of leaf. The form of incised leaves like those of Cichor- 
tum Intybus must be due to a factor or factors for differential 
periodicity, which determines that the rate or duration or both, of 
cell division, shall be greater in one part of the leaf than in another, 
thus producing the lobes and constrictions. 
In concluding, I wish to express my gratitude to Dr. R. A. 
Harper, under whose direction these investigations were under- 
taken, for the many helpful suggestions he gave me throughout 
the course of this work. I also thank Dr. A. B. Stout, from whom 
I obtained my chicory material, for his kind interest and help. 
DEPARTMENT OF BOTANY, 
OLUMBIA UNIVERSITY 
LITERATURE CITED 
Amelung, E. Ueber mittlere Zellengréssen. Flora 77: 176-207. 
1893. 
Conklin, E. G. Body size and cell size. Jour. Morph. 23: 159-188. 
f. I-12. I 
Familler, J. Die verschiedenen Blattformen von Campanula rotundi- 
folia L. Flcra 87: 95-97. f. I oO. 
Gates, R. R. The stature and eae of Oenothera gigas: De 
Vries. Arch. Zellforsch. 3: 525-552. 1909. 
Goebel, K. Einleitung in die experimentelle Morphologie der Latins 
Leipzig und Berlin. 1908. ws 
e, O. W., & Wawilow, N. Die anatomische Untersuchung 
einiger Haferrassen. Jour. Opitnoi Agron. 13: 830-861. 1912. 
[Russian. 
Reviewed in Bot. Centralbl. 123: 481, 482. : 
Jones, W. Neilson. Species hybrids of Digitalis. Jour. Genetics 2: 
71-88. pl. 3-5 + f. I-45. 1912. 
Keeble, F. Gigantism in Primula sinensis. Jour. Genetics 2: 163-188. 
pl. rr +f.1-5. 1912. 
Livingston, B. E. On the nature of the stimulus which causes the 
change of form in polymorphic green algae. Bot. Gaz. 30: 289-317. 
pl. 17, 18. 1900. 
Further notes on the physiology of polymorphism in green 
algae. Bot. Gaz. 32: 292-302. 1901. 
_ Sachs, J. Physiologische Notizen. VI. Ueber einige Beziehungen der 
specifischen Grésse der Pflanzen zu ihrer Organization. Flora 77: 
49-81. 1893. 
