SYMMETRY OF THE CENTROSPERM Æ. 283 
The curves clearly are composed of two subeurves, those of specimen 32 being regular 
and those of specimen 34 irregular. In the latter, commencing at the third ordinate 
the internode-segment and the succeeding displacement-segment form pairs that show 
8. 9. 
deviations from regularity always in the same sense, as if they had been abnormally 
shortened or lengthened by external circumstances. 
I also made measurements of two main stems of a species of Chenopodium, whose specific name I 
omitted to record. For this reason, I omit details of the measurements, which gave internode-curves 
capable of analysis into normal internode-subcurves disturbed by irregularities, and very regular displace- 
ment-subcurves of the ascending-descending type. 
CARYOPHYLLACE.E. 
This family, almost without exception (e. g. Pychnophyllum), shows cyclie phyllotaxis. 
And in accordance with this the genera Lychnis and Stellaria show internode-curves that 
are typical and regular. "This fact gains interest when it is remembered that in all the 
Caryophyllacez so far investigated the inception of the two leaves at a node is described 
as being not simultaneous. The statement is that in the vegetative region the leaf 
subtending the strengthened branch arises earlier than its fellow, whereas in the floral 
region the reverse is true. This peculiar behaviour is not in the least reflected in the 
internode-curves. If the opposite type of phyllotaxis is the primitive one in the 
Centrospermse, then this difference in the time of development of the two leaves at 
the caryophyllaceous nodes would seem to foreshadow the more advanced type of the 
Chenopodiacez, where the two leaves become separated. Even if the primitive phyllotaxis 
of the Centrospermee were spiral, the leaf-arrangement of the Chenopodiacez equally 
shows a transition to that of the Caryophyllacezm. In any case the leaf-arrangement of 
the Chenopodiacez seems to shed light upon the hitherto incomprehensible peculiarity 
of the successional development of the leaves in the Caryophyllacee. 
The shoots of Cerastium arvense examined did not show such regularity in their 
internode-curves ; yet the irregularities were not of the repeated, sudden, and extensive 
nature that indicates leaf-displacement. 
SECOND SERIES.— BOTANY, VOL. VII. 2U 
