288 EXPERIMENT STATION RECORD. 



"Most of the above inhibitorj'^ agencies operate by checking or arresting the initial 

 stages or primary processes of assimilation (tlecomposition of CO- and formation of 

 carbohy<lrati') ; but since the accumulation of cai'bohydrate affects assimilation, 

 any cause interfering with the rajiidity of its removal from the assimilatory cells 

 may also finally affect their power of assimilation. 



"Hence in the plant, as a whole, assimilation may be influenced by the causes 

 operating upon the general cell protoplasm and affecting the latter stages in the proc- 

 ess of assimilation (absorption, elaboration, and transformation of the assimilated 

 carbohydrates), either of the assimilatory cell itself or of the cells which are depend- 

 ent ni)on it for their supply of carbohydrate food material, or by a closure of the 

 channels through which these carbohydrates are removed. 



"Cells in which the green color of the chlorophyll grains is quite masked by the 

 presence of a brown or reddish-brown pigment may show a distinct power of assim- 

 ilation. If the reduction of the chlorophyll be complete assimilation ceases. 



"In certain cases isolated chlorophyll bodies may continue to assimilate for a short 

 time after removal from the cell to which they belong, 



"A developing leaf in which the chlorophyll grains are being formed ^ah iniUo' by 

 protoplasmic differentiation lacks at first the power of assimilation. The commence- 

 ment of assimilation is determined mainly by the development of the chlorophyll 

 pigment, but is also largely influenced by other indeterminate factors, probably 

 plasmatic in origin,"' 



Variation of seed as influenced by climate and soil, E. Gain 

 {Bev. gen. BoL, S {lS9f>), No. 91, pp. 303-305).— Th^ author gives a resum«3 

 of his own work,' and that of J. Kanlin- and A. Miintz' relating to this 

 snbject. The inlinence of moisture and drought have akeady been 

 considered in these pages at considerable length (E. S. R., 8, j). 3). 

 The investigations of Raulin with Miieat were conducted in two unlike 

 situations, Lyons and Ardennes, and the effect of changes in soil and 

 climate noted. The seed harvested at each station was divided and 

 portions from each place planted the succeeding year. In general, the 

 average weight of 100 grains of wheat grown at Lyons was less than 

 that grown at the other station. Three factors were found to influence 

 variation: (1) weight of seed, (2) local conditions, and (3) the ancestry 

 of the seed. One of the factors easily recognized is change of soil for 

 each generation, it being shown that a change in the chemical nature 

 of soil is favorable to increased production, and that there is a maxi- 

 mum and a minimum iniiuence dependent upon the succession of the 

 various soils. For example, the maximum for wheat is as follows : 

 Seed sown upon humus soil should have been grown on clay soil for the 

 best results; those sown on sandy soil should have been grown on cal- 

 careous soil; for clay and calcareous soils, the seed should have been 

 grown on sandy soils. Minimum results follow sowing wheat on humus 

 soil that has been previously grown on humus or calcareous soils, on sandy 

 soil where grown on humus or sandy soils, on clay when coming from 

 humus or clay soils, and on calcareous soils when previously grown upon 

 humus or calcareous soils. The principles here enunciated are thought 

 to probably apply to all kinds of plants, and this variation is believed 



'Ann, sci, nat, Bot,, ser, 7, 20 (1895), p. 63 (E, S. R,, 7, p, 366). 

 ■= Ann, Sci. Agron, ser, 2, 1 (1896), No. 2, p. 311- 

 3 Ibid., p. 161. 



