LECTURE XXVI. 



THE DISTRIBUTION OF THE PHASES OF GROWTH IN SPACE 



AND TIME. 



At the beginning of any new p'eriod of vegetation the buds of trees, sub-» 

 terranean rhizomes, bulbs, and tubers put forth new foliage-shoots and often 

 flowering stems also : in a relatively short time the previously naked trees are 

 covered with green foliage, and the meadows, gardens, and fields with flowering 

 plants. The plant-substance, which together with large quantities of water 

 affords the constructive material for this rapid growth, has been produced in 

 the previous period of vegetation by means of assimilation, and stored up in 

 the wintering organs of the plant in the form of reserve-materials, now to be made 

 use of for growth. 



But even the organs themselves, the foliage and flower-shoots which make 

 their appearance duririg the first warm days of the spring, had already been produced 

 in the previous suminer and autumn ; but, small and in part even microscopic in 

 size, had passed into a condition of rest before further development. With the 

 beginning of the new period of vegetation they renewed their activity; in a word 

 the organs themselves, as well as the materials necessary for their further growth 

 passed the winter in an undeveloped, embryonic condition. It is the same also 

 in the case of seeds, which contain in addition to the young developing organs 

 of the embryo the nutritive materials for their first growth also. 



The new germinal and foliage-shoots and flower-stems having been formed 

 then in the spring at the cost of the reserve-materials presei-ved through the 

 winter, and a widely-spread root system having been developed in the soil 

 assimilation — i. e. the formation of new plant-substance — ^is renewed ; and according- 

 to the nature of the plant, this is soon again employed for the formation of new 

 organs, or deposited in the reservoirs of reserve-materials for the next year or 

 both processes are combined in very various ways. 



It is easy to conclude from these remarks, which lend themselves directly to 

 the inference, that nutrition and growth need not coincide either in time or in 

 space. Nutrition — ^i. e. the production of vegetable substance — is usually carried on 

 most energetically at a time when the growth of the organs in the main has already 

 taken place ; and we find the most vigorous growth taking place at the beginning 



