211 



Tfiermal constants for the hlo-^somiiuj <uid ripcniiiy of 8S9 plants, etc. — Ctjutinued. 



Designation of plant: onU-r. genus, and spoi'ies 



XCVII. Papilionaceiv [(?.—; see G. 52]— Cor.tinued. ^..^^ 



(><85) Cercis canadensis L '. May 8^ 149 



(886) Cereis siliqnnstrum L May 16 1 511 



(887) Gleditschia triacanthos L. inerniis June 5 I 756 



(888) Gymnocladns canadensis Lam June 4| 763 



(889) Cassia marylandiea L July — 1 , 631 



Oct. 5 \ 2,430 

 Sept. 20 I 2,332 



■ 54. Very rarely blossoms. 



57. The fruit ripens during the following season. 



168 and 175. Did not bloom during the ten years. 



179 and 1S9. Tree too young to blossom. 



203. The concealed blossoms can not be accurately observed. 



270 and 271. The dates of blossoming are too variable to allow of determining a thermal constant. 



304. These figures obtain for moist years, but for dry years we have September 9 and 2237, respec- 

 tively. 



308. Blossomed only once during these ten years. 



518. The blossoming of the tree is not easy to observe. 



677. The tree died in 1855. 



580 and 581. Too young to blossom. 



702 and 775. Did not blossom. 



716. Blo-ssomed only once and died in 18-57. 



756. Did not blossom and died in 1856. 



800. Dates are too variable to allow determining a thermal constant. 



834 and 880. The dates when the hull hardens and colors and when it springs open, allowing the 

 fruit to fall, are both given. 



LINSSER. 



The most elaborate and, I believe, the most important investigation 

 into the relation between plant life and climate is that published by 

 Karl Linsser in a first memoir (St. Petersburg, 1867) and in a sec- 

 ond memoir of 1869. My personal association with him during 1865 

 and 1866 greatly stimuhited my own early interest in the subject. 

 The conclusions arrived at by Linsser are based upon the study of all 

 available European observations. His knowledge of physics and 

 skill in numerical computations as the chief of the computing divi- 

 sion of the Imperial Astronomical Observatory at Poulkova has 

 given his results a precision based on the well-established principles 

 of probabilities and a clearness of interpretation that specially com- 

 niend them to the physiological botanist. Linsser states that the 

 l)rincipal hypotheses that had up to his time been framed as to the 

 form of the connection between the phenomena of temperature and of 

 phenology are the following three: 



(1) That for the same plant the same stage of vegetation occurs 

 from year to year on the attainment of the same mean daily temper- 

 ature. 



