266 
average of ten years there is no appreciable difference between the 
results. 
Duration, in days, from sowing to heading of winter wheat, at Montsouris, France. 
| | | | ever 
| Average for 
| | | | 1872-1881. 
Date of sowing. | 1872. | 1873. | 1874. | 1875. | 1876. | 1877. | 1878. | 1879. | 1880. | 1881. | 1882. |. ——___ 
| Dura- 
| | | | ‘tion. Date. 
| bara Te 
September 22---| 152 67 8v | 58 91 57 | 61 | 167 160 85 | 154]! 99] Dec. 30 
September 29..-| 158 72) 116 113} 147) 64 | iliKa))|) alvat 161 92) 159 | 120 | Jan. 27 
October 6 ___---- 161} 80} 161 15D alee bs: | 84} 135} 180 | 161 | 136 157 | 141 | Feb. 24 
October 132. -—-2 | 168 | 90 164 | 172 164 88 | 140] 173 | 164] 147 | 155 147 | Mar. 9 
October 20......] 168} 133] 163| 175} 163| 107/ 138) 178| 164] 148] 150| 154 | Mar. 23 
October 27... 163) 140} 162) 174) 160 106 | 145) 185 | 164) 147) 152] 155 | Mar. 31 
November 3 ....| 162| 141| 158] 172] 156| 107| 156| 192) 162] 141| 146| 154| Apr. 6 
November 10...| 155 | 140| 158] 171) 159/ 108| 156] 175| 158] 128| 146| 151| Apr. 10 
November 17_..| 148 | 134] 153) 165| 156| 128) 150) 168] 153] 141] 144| 149 | Apr. 15 
November 24 ...| 141] 134) 148 | 159 | 160) 125) 147 | 162 | 147] 135) 141 | 145 | Apr. 18 
December 1.....) 134| 136 | 142] 154] 143] 123] 148] 156) 140] 181 | 136] 140 | Apr. 20 
December 8.__.- 127 | 182] 185| 148] 186] 120} 198| 149| 188] 127] 129| 135 | Apr. 22 
December 15....| 120) 126] 128] 141) 129) 115) 131) 142| 126] 124| 122) 128 | Apr. 22 
December 22....| 113 | 129] 121 | 184] 124] 111] 126] 135) 119| 126] 118| 124-| Apr. 25 
December 29___- 18 TRAP AEE key 120) a 1a 131 | 112] 123) 111] 118 | Apr. 26 
This table shows that on the average of ten years the seed that was 
sown, e. g., on the 27th of October and required one hundred and 
fifty-five days to head, is that which took the longest time; for sow- 
ings before that date, as well as after it, the durations steadily 
diminish; in other words, this sowing is that whose development 
was the most retarded by the winter cold. If we compare this table 
with those given by Marié-Davy, showing the frosts, we find a com- 
plete inversion in the chances of injury from frost; wheat as a green 
plant has as little to fear from frost as has the dry grain. But 
during and after the formation of the embryo seed, as well as during 
germination, on the contrary, frost is very injurious, and if the 
embryo is seized by frost it perishes. If this accident occurs it is 
possible that the progress of heading may permit a new formation 
of embryo to replace those which have perished. Such accidents 
must have occurred to the seed sown in the hope of reaping an early 
harvest in 1874, 1875, 1876, 1877, 1878, and 1881, but did not occur 
in 1882. This accident is not incompatible with an excellent harvest, 
as we see in the case of 1874, but it causes a decided retardation of 
ihe harvest, as in 1877. The mean of the ten years shows that the 
heading occurs at an epoch in the spring when the mean temperature 
of the air is between 6° and 13° C., and when the rainfall is generally 
abundant, so that at this epoch damage does not generally occur to 
the grain; only in case of the sowing of September 29, 1878, did the 
en ea 
Se 
