Maat 
185 
mine the epoch of the awakening of the plants in the first two places, 
but in the last mentioned the acceleration is forty-one days. This 
acceleration is also very great at the other stations of England, as 
well as at Valogne, which has also probably a sea temperature. 
It has also been impossible for me to fix the time of awakening for 
places where the winter is the most rigorous, such as Lapland, 
Sweden, and the United States. We have seen, however, that there 
is twenty days retardation in places where the mean temperature is 
very little below zero. Jever seems to be an exception to this rule; 
but. Fhe results obtained in this place were only deduced from three 
observations. 
The epoch of leafing corresponds, as we have said, with the end of 
March and the month of April, and that of the flowering with the 
months of May and June. The first includes the commencement of 
spring, the other the end of it. Thus the temperature of Brussels 
in spring is 10° C. The greatest variations besides are at Naples and at 
Alais. It is also in these places that the leafing takes place first. 
Venice, Parma, and Guastala are very little in advance, but the 
month of March and the beginning of April are scarcely any warmer 
than at Brussels. The difference of temperature is only felt in a 
marked manner in the following months. The flowering also takes 
place about eighteen days sooner. 
Polperro, in regard to leafing, is about ten days in advance. ‘The 
temperature in March is much higher than that of Brussels, while 
in April it is about the same. The advantage is lost in the following 
months, when, as regards flowering, Brussels is in advance of Pol- 
perro, as well as of the localities in England. 
Brussels is about eighteen to twenty days ahead of the towns of 
Holland and Germany in the epoch of leafing, and is behind in the 
complete to allow of undertaking such a task. The first chart would have shown 
by a series of lines drawn over Europe the awakening of plants for each ten 
days, that is to say, a first line would indicate the localities where the awakening 
first takes place immediately after the coldest day of the year, which with us 
is about the 20th of January; a second line would pass through places where 
the awakening is on an average ten days later, and so on. Another system of 
similar lines traced upon a second chart would have indicated in the same way 
the beginning of budding, always proceeding by intervals of ten days. We 
should also have made similar charts for flowering and ripening and the fall 
of the leaves. By comparing these charts we should be able to see at a glance 
the principal changes which take place in these various systems of lines. In 
order to complete this study we should imagine other systems of lines relating 
to temperatures. Thus one system would show the localities in Hurope where 
frosts first cease, always advancing at intervals of ten days; then another sys- 
tem for places which, at successive intervals of ten days, and beginning from the 
awakening of the plants, have reached a sum total of temperatures amounting 
to 188° C., corresponding to the epoch of leafing; further, a third system of 
lines which should pass through places that, counting from the time of awaken- 
ing, have successively attained the total number of degrees of temperature 
necessary for the flowering of plants; and so on for further systems. 
The charts relating to vegetation and those relative to temperatures would, by 
comparing them, give much curious information. Unfortunately the observa- 
tions we possess of daily temperatures are still as rare as those of the flower- 
ing. I have therefore been compelled to renounce that portion of my work. 
