Jan. 1896.] BOTANICAL SOCIETY OF EDINBURGH. . 497 



through which very dry air at a pressure of about 10 to 20 

 M.M. of mercury was slowly aspirated. After 12 hours the 

 boats were taken out and again weighed, the loss giving 

 the amount of moisture in each case. 



Having now described as fully as necessary the method 

 of experiment followed, I will proceed to discuss shortly a 

 few of the results obtained under the five heads before 

 mentioned. 



1. The Quantity of Carbonic Anhydride exhaled. — 

 These experiments show clearly the influence of moisture 

 on the amount of this gas produced ; an increase of 

 moisture always producing a corresponding increase in the 

 carbonic anhydride. When the moisture is considerably 

 increased it is invariably found that during the first day or 

 two of germination the quantity of carbonic anhydride 

 excreted is a little less than for lower degrees of moisture, 

 but the grain soon recovers its partial drowning as it were, 

 and increased activity due to increase of moisture soon 

 asserts itself. The effect of moisture on the production of 

 carbonic anhydride is clearly shown in Table I., and graphic- 

 ally in the curves on diagrams Figs. 1 to 4. I need give 

 but one instance here : — Scotch Chevalier barley steeped 

 for 24 hours was found to contain 3 5*90 per cent, water. 

 On germinating for 14 days at constant temperature the 

 carbonic anhydride collected weighed '2330 gramme. The 

 same barley steeped for 96 hours contained 44*78 per 

 cent, water, and produced in 1 4 days, at the same tempera- 

 ture, "4852 gramme carbonic anhydride. So for an 

 increase of moisture amounting to 8*88 per cent, the 

 quantity of carbonic anhydride was more than doubled. 



2. The Dry Weight of the Embryo at the end of the 

 Germinative Period. — Table II. gives the results obtained 

 on this point. Corn germinated for 14 days, after a 96 

 hours' steep, gives a dry embryo weighing rather more 

 than double that obtained when the steep is only 24 hours. 



3. The Eatio of the Weight of Carbonic Anhydride 

 exhaled to the Increase in the Dry Weight of the Embryo. 

 — When the number representing the increase in the dry 

 weight of the embryo during germination is divided by 

 the weight of carbonic anhydride exhaled, it is found that 

 the product increases in value as the quantity of moisture 



