The influence of mechanical resistance on the development 
and life-period of cells. : 
FREDERICK C. NEWCOMBE. 
Introduction. 
The question as to what actively growing plant tissues will 
do when their growth is checked by external mechanical re- 
sistance had received but small notice in literature till the 
appearance of Pfeffer’s! latest published work. Some years 
ance and that the wood elements expanded more slowly. 
Krabbe® by applying a graduated pressure to the trunks of 
trees, found the cambium cells uninfluenced either in size of 
nmen or in thickness of wall both when the cambium was 
forming new cells under various pressures and when the form- 
ation of new cells was entirely stopped by sufficiently increas- 
: - This author confirmed De Vries’ observ- 
ation stated above, that the time between the formation of a 
at the subepidermal collenchyma was ab- 
This thickening he used to strengthen 
than pn believing that cell-walls grew thicker 
face ermally when they could not reach their normal sur- 
extension. 
Pfeffer in the 
Several s 
ty of growth, 
-'€ work referred to enclosed the root-tips of 
growin Eevee of seedlings, the stems of a few species, the 
"Ny Lala of Chara and Nitella, and the filaments of Spi- 
tions h 'N gypsum casts. From the behavior of these prepara- 
She deduces these results: 
"Pfeffer, Dy Rae Ree Se arate 
der Wine, ck und Arbeitsleistung. Abhandlungen der kinig. sich. Gesells. 
De ‘ Schaft 20: eee | 
iene’, ties, De lin 
fluence de la pression du liber sur la structure des couches 
fe Mittheitue® les. Extrait des Archives Neerlandaises 1876. Also, Vorlaii- 
a 8, Flora —: 97-102. 1875, 
in nah a das Wachsthum des Verdickun gsringes und der, jungen Holz- 
‘Wortmann pobangigkeit von Druckwirkungen. Berlin, 1 
1884. 
= tage zur Physiologie des Wachsthums. Bot. Zeit. 47: 286. 
