Book I. EVIDENCE OF VEGETABLE VITALITY. 189 



in opening in North America than in the same latitudes in Europe, because the surface of the earth is 

 higher, or the winters more severe. . 



H50 Maturation of the fruit. Plants exhibit as much diversity in the warmth and length of time neces- 

 sary to mature their fruit as in their frondescence and flowering; but the plant that flowers the soonest, 

 tloes not always ripen its fruit the soonest. The hazel-tree, which blows in February, does not ripen its 

 fruit till autumn ; while the cherry, that does not blow till May, ripens its fruit in June. It may be re- 

 garded, however, as the general rule, that if a plant blows in spring it ripens its fruit in summer, as in the 

 case of the currant and gooseberry ; if it blows in summer it ripens its fruit in autumn, as in the case of 

 the vine ; and if it blows in autumn it ripens its fruit in the winter. But the meadow-saffron, which 

 blows in the autumn, does not ripen its fruit till the succeeding spring. 



851. Such are the primary facts on which a Calendarium Flora;, should be founded. 

 They have not hitherto been very minutely attended to by botanists ; and perhaps their 

 importance is not quite so much as has been generally supposed ; but they are at any 

 rate sufficiently striking to have attracted the notice even of savages. Some tribes of 

 American Indians act upon the very principle suggested by Linnaeus, and plant their 

 corn when the wild plum blooms, or when the leaves of the oak are about as large as a 

 squirrel's ears. The names of some of their months are also designated from the state 

 of vegetation. One is called the budding month, and another the flowering month ; 

 one the strawberry month, and another the mulberry month ; and the autumn is desig- 

 nated by a term signifying the fall of the leaf. Thus the proposed nomenclature of the 

 French for the months and seasons is founded in nature as well as in reason. 



852. Cold. As the elevation of temperature induced by the heat of summer is es- 

 sential to the full exertion of the energies of the vital principle, so the depression of 

 temperature consequent upon the colds of winter has been thought to suspend the ex- 

 ertion of the vitalenergies altogether. » But this opinion is evidently founded on a mistake, 

 as is proved by the example of such plants as protrude their leaves and flowers in the 

 winter season only, such as many of the mosses ; as well as by the dissection of the yet 

 unfolded buds at different periods of the winter, even in the case of such plants as pro- 

 trude their leaves and blossoms in the spring and summer, and in which, it has been 

 already shown, there is a regular, gradual, and incipient developement of parts, from 

 the time of the bud's first appearance till its ultimate opening in the spring. The sap, 

 it is true, flows much less freely, but is not wholly stopped. Du Hamel planted some 

 young trees in the autumn, cutting off all the smaller fibres of the root, with a view 

 to watch the progress of the formation of new ones. At the end of every fortnight he 

 had the plants taken up and examined with all possible care to prevent injuring 

 them, and found that, when it did not actually freeze, new roots were always uniformly 

 developed. 



853. Energies of life in plants like the process of respiration in animals. Hence it fol- 

 lows, that even during the period of winter, when vegetation seems totally at a stand, 

 the tree being stripped of its foliage, and the herb apparently withering in the frozen 

 blast, still the energies of vital life are exerted ; and still the vital principle is at work, 

 carrying on in the interior of the plant, concealed from human view, and sheltered from 

 the piercing frosts, operations necessary to the preservation of vegetable life, or protru- 

 sion of future parts ; though it requires the returning warmth of spring to give that 

 degree of velocity to the juices which shall render their motion cognizable to man, as 

 well as that expression to the whole plant which is the most evident token of life : in the 

 same manner as the processes of respiration, digestion, and the circulation of the blood 

 are carried on in the animal subject even while asleep ; though the most obvious 

 indications of animal life are the motions of the animal when awake. Heat then 

 acts as a powerful stimulus to the operations of the vital principle, accelerating the mo- 

 tion of the sap, and consequent developement of parts ; as is evident from the sap's 

 beginning to flow much more copiously as the warmth of spring advances, as well as 

 from the possibility of anticipating the natural period of their developement by forcing 

 them in a hot-house. But it is known that excessive heat impedes the progress of veget- 

 ation as well as excessive cold ; both extremes being equally prejudicial. And hence 

 the sap flows more copiously in the spring and autumn, than in either the summer or 

 winter ; as may readily be seen by watching the progress of the growth of the annual 

 shoot, which, after having been rapidly protruded in the spring, remains for a while 

 stationary during the great heat of the summer, but is again elongated during the more 

 moderate temperature of autumn. 



854. Stimularity. There are also several substances which have been found to operate 

 as stimulants to the agency of the vital principle when artificially dissolved in water, and 

 applied to the root or branch. Oxygenated muriatic acid has been already mentioned : 

 and the vegetation of the bulbs of the hyacinth and narcissus is accelerated by means of 

 the application of a solution of nitre. Dr. Barton, of Philadelphia, found that a de- 

 caying branch of liriodendron tulipifera, and a faded flower of the yellow iris, recovered 

 and continued long fresh when put into water impregnated with camphor ; though 

 flowers and branches, in all respects similar, did not recover when put into common 

 water. 



