152 The Botanical Gazette. [April, 
The cells of the meristematic zone were in all cases living and 
normal in appearance at both periods of examination. 
The growth of the leaves of Allium cepa is also intercalary, 
the meristem is at the leaf-bases. Several experiments were 
made on this plant by including within a cast the upper part 
of the bulb and the young leaves which had started from it. 
The cast was then fastened by bandages to the bulb so that 
bulb and cast could not separate, yet so that the roots could 
grow out freely. The preparations were examined, some at 
the end of two weeks, some after thirty-one days. The te- 
sults were the same in all cases. The meristem remained 
alive, and growth was resumed upon removal of the casts. 
The effect on the cambium of arresting its growth by ex- 
ternal resistance has been determined by enclosing within 
gypsum casts the stems of many plants both herbaceous and 
woody. To prevent by this method all extension or growth 
in the cells within is impossible, since the presence of inter- 
cellular spaces always affords some room, and the resistance 
of vessels is not sufficient to withstand the force of turgor 
the thin-walled cells. Thus, though the cambium has not 
been held in these experiments, and could not be, in a state 
of absolute rest as regards growth, its activity in this direc- 
tion has been, as will be seen, very slight. The amount of 
entirely on the room it can make for itself, and differs there- 
fore in different species of plants, and differs also in the same 
species, since the size of the intercellular spaces and the tur 
gor of a tissue will differ with age. In young stems of many 
plants the primary meristem of the fibrovascular bundles has 
been preserved in an almost quiescent condition for seve 3 
weeks. Rarer examples of long continued rest have bee 
furnished by Lamium garganicum, Vicia faba and Dahlia ee 
tiabilis in which so slight was the development within 
casts that for 40, 50 and 120 days respectively the formati®® 
of the interfascicular cambium was prevented, though it < 
formed immediately below and above the limits of the 
and the growth of the plants as a whole continued. Ye wi 
withstanding this long rest the primary meristem was appa 
ently and undoubtedly capable of farther active growt a 
In cases where the casts were applied after the meer : 
zone was completed, there are many individuals, repre 
several species, bearing testimony to the long pres 
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