Polytechnic Association. 575 



this country seeds may last longer than in England. The equal tem- 

 perature found in the soil tends to preserve the vitality of seeds. 



Dr. L. Bradley — I see nothing mysterious in the appearance of a 

 crop of oaks in the place from which a pine forest has been cleared 

 off. Everything is changing, appearing and reappearing. "We have 

 a succession of crops ; why not of forests? May there not have been, 

 previous to the pine crop, beech, maple or oak crops ? It seems to 

 me reasonable to suppose that. 



Dr. P. H. Van der Weyde — We don't get a wheat crop after rye 

 without sowing it. 



Dr. J. W. Richards — Some classes of seeds will preserve their 

 vitality longer than others. Oleaginous and aromatic seeds retain 

 their vitality ; and so do the lower grades of vegetables. Mosses will 

 grow after having been dried two or three hundred years. With 

 regard to the seeds never having been found, it is no evidence that 

 they were not in the soil. The germ is very small, and the other 

 portions of the seed may have been destroyed and the germ may be 

 preserved. In the Mohawk flats, a furrow cannot be turned up with- 

 out producing an enormous crop of mustard. It would be interesting 

 to search for the mustard seeds, which, being aromatic and oily, would 

 resist the ordinary influences of moisture and temperature for a long 

 time. The facts referred to have given rise to vague ideas about the 

 creation or formation of new plants without seed. While it is easy 

 for me to conceive that the hand that created the first plant could 

 create another, we have no proof of such creation ; and it would be 

 very interesting to make a search for the existence of seeds in the soil. 



Prof. Phin — I question whether the oak would grow from the 

 germ alone, without the pabulum furnished by nature to sustain it. It 

 was the suggestion of Henry Thoreau that it was the squirrels which 

 brought the acorns from a distance and buried them in the pine for- 

 ests, in such quantities that you could not cut down a forest of pine 

 trees beneath which a crop of oaks had not been sown by the squir- 

 rels within a few years. 



Dr. Richards — It has been found that seeds which would not ger- 

 minate when exposed to the ordinary influences of the atmosphere, 

 would grow on being moistened with preparation containing chlorine. 

 Some change of circumstances may revivify a germ which, under ordi- 

 nary exposure, would be destroyed. 



The President — Probably, the reason why the pine does not grow 

 so well where it has just been cut down is, that the soil is exhausted 

 of the peculiar qualities required for pine ; and from that very fact. 



