241 
Many of the plants observed by Hoffmann show such discordant 
sums from year to year as to prove that his method has no meaning 
for them, but for others the agreement is such that he recommends 
them to be observed in connection with the cbservations of the sun- 
shine thermometer, as follows: 
For the following plants observe the temperature sums from the 
first swelling of the buds to the first flower blossom: Castanea vesca, 
Bupleurum falcatum, Corydalis fubacea, Dianthus carthusiano- 
rum, Lonicera alpigena, Salix daphanoides, Syringa vulgaris, Amygq- 
dalus nana, Alnus incana, Alnus viridis, Atropa belladonna, Betula 
alba, Crataegus oxyacantha, Larix europaea (up to the date when 
the pollen first falls from the anthers), Ligustrum vulgare, Lonicera 
éatarica, Prenanthes purpurea, Prunus padus, Prunus spinosa, Rham- 
nus frangula, Ribes aureum, Rosa arvensis, Rosa alpina, Salix caprea, 
male (for the catkin, or the flowers of the willow, the beginning of 
pollination, as ascertained by a light stroke on the flower, is to be 
considered as the date of the first blossom). 
Hoffmann also applies his summation of sunshine maxima tempera- 
tures to the interval from January 1 to the ripening of the fruits 
and shows an excellent agreement between the numbers for 1880 and 
those for 1881 at Giessen. 
In the Zeitschrift for 1884 Hoffmann gives his results for 1889, 
1883, and 1884 as collected in the preceding table and says that the 
vexed question of the thermal constant for vegetation is still far 
from being settled; either temperature and vegetation are independ- 
ent of each other, which no one can easily believe, or they stand to 
each other in a relation for which the correct expression is still 
unknown. Pfeffer in his Pflanzen Physiologie (Vol. II, p. 114) has 
stated that the approximate uniformity of the sums of temperature, 
from year to year, can only mean that, in general, for each year the 
heat received from the sun amounts to about the same sum total for 
the same date annually; but this is not in strict accordance with 
facts, for if it were true a small change in the date should make a 
small change in the sums, which is not always the case. Thus, if 
for Linosyris vulgaris the dates of blossoming are August 15, 18, or 
20, the sums from January 1 for different years will be as follows: 
Year. Aug. 15. | Aug. 18. | Aug. 20. 
The S38 25 pens stl A a ean 4, 555 4, 637 4,698 
NS83 ef Se et SSS iS SCE ESE Eee et a 2 4,597 4,670 4, 728 
Leelee SS SESE Bee cps ee ie ee ae Aa Tee ne ee Se eS 4, 363 4, 452 4,500 
From these figures we see that the sums vary from year to year 
quite independently of the change of date. 
The thermometer B,, similar to B,, having been sent to Upsala for 
observations at that place, it gave from January 1 to the first blossom 
2667—05 Mm——16 
