PRESERVATION OF VEGETATIVE POWERS IN SEEDS. 51 



A. Retrospective Experiments. 



1. By collecting samples of ancient soils from situations where vegetation 

 cannot now take place, and by exposing these soils to air, light, warmth, and 

 moisture, to ascertain whether any, and if any, what, species of plants spon- 

 taneously vegetate in them. 



N.B Care must of course be taken that no seeds obtain admittance 



into these soils from external sources, — such as the air or water intro- 

 duced to promote vegetation. 

 These ancient soils are either natural or artificial deposits. 

 The natural deposits belong either to past geological periods or to the re- 

 cent period. 



a. The deposits of past periods are either secondary or tertiary. 



N.B. — There seems every reason to believe that the age even of the 



latest of these deposits is far beyond the maximum period through 



which vegetative powers can be preserved ; yet as many accounts are 



recorded of seeds vegetating spontaneously in such soils, it would be 



well to set these statements at rest by actual experiment. 



In such experiments, state the formation, and describe the geological phse- 



nomena of the locality, together with the depth from the present surface at 



which the soil was obtained. 



h. Natural deposits of the recent period may be classed as follows : — 

 Alluvions of rivers. 

 Tidal warp land. 

 Shell marl. 

 Peat. 

 Surface-soil buried by landslips. 



Ditto ditto by volcanic eruptions. 

 In these cases, state the nature of the soil, the depth from the surface, &c.; 

 and especially endeavour to obtain an approximate date to each specimen of 

 soil, by comparing its depth from the surface with the present rate of depo- 

 sition, or by consulting historical records. It would be well to submit to ex- 

 periment a series of samples of soil taken from successive depths at the same 

 locality. 



c. Artificial deposits are as follows : — 

 Ancient tumuli. 

 Ancient encampments. 



The soil beneath the foundation of buildings. 

 The soil with which graves, wells, mines, or other excavations have 



been filled up. 

 Ridges of arable land, &c. 

 In these cases, state, as before, the depth from the surface, and ascertain 

 from historical sources the approximate age of the deposit. 



2. By trying experiments on actual seeds which exist in artificial reposi- 

 tories. These are, — 



Seeds in old herbaria and botanical museums. 



Seeds obtained from mummies, funereal urns, at Pompeii, Hercula- 



neum, &c. 

 Dated samples of old seeds from nurserymen and seedsmen. 

 In these cases, state the circumstances in which the seeds have been pre- 

 served, and their date as nearly as it can be ascertained. 



B. Prospective Experiments. 



In this department of the inquiry, it is proposed to form deposits of va- 

 rious kinds of seeds under different conditions, and to place a portion of them 



