124 AGRICULTURAL REPORT. 
never seen to go without corn in the ear.” It is curious. to determine 
at what period these cerealia put forth the ear in the various parts of 
the United States, compared with Belgium and other parts of Europe. 
Two methods of observation may be employed, namely, with plants 
wild or cultivated : the former is uncertain, and presents scant facilities, 
as the observer would have to traverse large tracts and different regions, 
and never be sure of observing the same plant the second time. It is 
‘ essential that the daily observations of plants fixed upon for comparison 
should be made on individuals planted in an airy garden; they should 
neither be sheitered nor exposed to a south wall. ‘Frees should be 
selected in open fields, because woods always afford unequal shelter. 
Indications of periods for foliation should be made when the leaf-buds 
first burst; and, for flowering, when the anthers are visible; the same 
will apply to the Composite. The foliation period presents. difficulties,, 
especially in spring, and therefore I propose to select that moment 
when, in advance of vernation, the upper face of the outer leaves be- 
comes exposed to the action of the atmosphere and commences its vital 
functions. [ructification should be noted at the time of the dehiscence 
of the periMirp in dehiscent fruits, which form the largest number; in 
the indehiscent fruits it should be noted when they have arrived at 
maturity. Lastly, the defoliation should be noted when the most of 
the leaves have fallen, it being fully understood that what relates to 
leaves can only apply to woody plants, excluding the overgreens, whose 
defoliation is successive. s . 
To the above observations should be added the modifications which 
occur in odors, and colors of flowers, leaves, &c.; also the daily indica- 
tions of mean temperatures, or, still better, the maximum and minimum. 
_ 2. Observations for the diurnal pericd.—Independently of the annota- 
tions of each day, which form the calendar of Flora, there should be regis- 
tered in each locality the hour at which certain plants expand and close, 
when they perform these functions at a determinate time. The daily 
registration of these results being too tedious, it is proposed to limit 
them to the eguinoxes and summer solstice.* 
Quetelet, endeavoring to apply the calculation of probability to peri- 
odical phenomena, makes the following remarks: Natural sciences have 
been until the present time less amenable to mathematical theories than 
physical sciences, notwithstanding they offer many favorable openings 
for calculable combinations, and especially the calculations of proba- 
. bility. A striking example exists in relation to periodical phenomena, 
which may be expressed largely by dates, and translated into numbers. 
The causes which it is essential to comprehend are those having an 
influence upon the progressive development of plants. We may here 
limit our consideration to the predominant causes, as they occur in 
physical phenomena, and return subsequently to secondary causes. I 
shall arrange in four principal classes those causes which may influence 
the flowering of a plant. 1st. The geographical causes; such as lati- 
tude, longitude, and altitude. 2d. The local causes; such as the nature 
of the soil, the exposure, and the quantity of light. 3d. The individual 
causes; such as the age and vigor of the plant. 4th. The meteorologi- 
cal causes ; such as the temperature, the nature of the winds, the damp- 
ness of the air, the quantity of rain, the state of the sky, &c. 
It would be very difficult to study all these causes simultaneously, 
and to comprehend the influence appertaining to each; the surest means 
would be to proceed from the simple to the composite. To eliminate the 
-* Bulletin de l’Académie des Sciences de Bruxelles, 1842. Vol. ix. pp. 65-95. 
