GERMINATION. 645 



same individual plant under apparently identical conditions. In general 

 terms, the length of time required is long in proportion to the lowness of 

 the temperature, the absence or presence of perisperm, its nature, the 

 depth of sowing, &c. Seeds enclosed within a hard pericarp, endocarp, 

 or testa, often remain a year or even more before germination ; but in 

 such cases the process may be accelerated by soaking the seed. Some 

 seeds require to be sown at once or they lose their germinating power ; 

 others retain their vitality for a great number of years, though the stories 

 relating to the germination of seeds taken from Egyptian mummies and 

 Roman barrows will not bear the test of close examination. Better 

 authenticated statements have shown that some seeds have retained their 

 vitality after more than a century. Out of 368 species sown at Geneva 

 by Alphonse de Candolle, 17 only grew after a lapse of 15 years. 

 Fifteen out of 20 seeds of Dolichos grew after this period, 6 out of 20 

 of Lavatera, of the other 15 only 1-3 grew. Out of 288 genera whose 

 seeds were sown under the auspices of the British Association by Dr. 

 Daubeny and others, it was found that the majority had lost their vitality 

 altogether after having been kept 10 years. Thirty-four species, about 

 one seventh of the whole number, retained their vitality after 10 years, 

 20 species after 20 years, and 2 only, both Leguminosse, maintained their 

 vitality after 40 years. In both sets of experiments the greatest in- 

 stances of longevity were found among the Leguminosae, which are desti- 

 tute of perisperm, while the IJmbelliferae, which have perisperm and much 

 essential oil, seemed to lose vitality particularly soon. 



Circumstances retarding Germination. These will have been gleaned from 

 what has preceded. Deprivation of water or oxygen gas, too low or too 

 high a temperature, will all retard or even prevent germination, in extreme 

 cases, by destroying the vitality of the embryo. Pure phosphorus retards 

 germination, while anilin is stated to stop it completely, as arsenious acid 

 and other poisons do. Exposure to light does not of itself retard germi- 

 nation, other conditions being equal. 



Changes during Germination. When germination begins the soluble 

 matters contained in the seed are used up, while the insoluble ones are so 

 modified as to become soluble. The ternary ingredients, especially starch, 

 become converted into dextrin and glucose under the influence of a nitro- 

 genous substance, diastase, which acts as a ferment. Thus in the process 

 of malting, which is nothing but the germination of Barley stopped at a 

 certain stage, the starch becomes converted into sugar, thus : starch with 

 a composition of 36 H 30 O 30+4 HO = 2 Glucose 2 (0 12 H 12 12) 

 and Dextrin C 12 H 10 10 (Musculus). What brings about the ultimate 

 transformation of grape-sugar, or glucose, or of dextrin into cellulose is not 

 known. Fatty substances lose a portion of their carbon and form glucose. 

 Nitrogenous substances during germination undergo analogous transfor- 

 mations ; thus, among Leguminosae, the albuminoid matters become trans- 

 formed into asparagm, a soluble nutritive substance, which is conveyed 

 from cell to cell, according to the requirements of the case. The trans- 

 formation of the albuminoids into asparagin takes place as well in 

 obscurity as under the influence of light. Oxygen is fixed during the pro- 

 cess, and C and H are liberated, the sulphur being oxidized and changed 

 into sulphuric acid. Gorup-Besanez has also shown that in Beans there 

 exists a diastasic ferment capable not only of effecting the transforma- 



