LONGEVITY OF SUBMERGED SEEDS 331 



In February 1904, a freshet carried away a section of the lower 

 dam, and the bed of St. John's pond was laid bare for the first 

 time in over seventy years. With the opening of spring thore 

 came into existence a covering of vegetation, ren'arkable alike 

 in quantity and diversity, over nearly' the entire pond-bed. The 

 higher portions of the pond-bed, which were quickly drained, 

 soon became hard like sun-dried bricks, and deeply f ssured and 

 on these portions the phaenogamous vegetation was sparse 

 (fig. 1), but in the lower portions, which remained moist through- 

 out the summer, the carpet of vegetation became quite dense 

 as seen in the background in f gure 1 and in f gure 2. An enumer- 

 ation showed the presence of more than 140 species of flowering 

 plants, besides many mosses and at least one liverwort, whose 

 small circular mat-like thalli were not specifically identified. 

 A small portion of the plants which came to bloom during the 

 summer were perennials, including, for example, several species 

 of Aster and So!ida';o, which m^ust have developed from fragments 

 of rootstocks which had been carried into the pond by the trib- 

 utary streams. A fine cluster of Utricularia gibba which had 

 not been previously listed from Cold Spring Harbor was also 

 included. Its vegetative fronds had been found in the waters 

 of the pond but had not been identified because the descriptions 

 of this species in the manuals have been written from the flowering- 

 specimens and do not correctly represent the vegetative stage. 

 The great majority of the species, however, were annuals, and 

 must have developed from seeds lying in the mud. 



In view of the emphasis which is generally laid upon the neces- 

 sity of keeping seeds dry in order to maintain their vitality, the 

 .question immediately arose as to whether the millions of seeds 

 represented by this dense herbaceous carpet might have lain in 

 the mud since the preceding autumn or even longer, or whether 

 they must have been brought in by various distributing agents 

 after, or at any rate not long before, the draining of the pond in 

 the spring. 



To get an experimental answer to this question, seeds of 58 

 species representing a wide relationship, were collected on Novem- 

 ber 5, 1904, and placed in a large glass jar which had been filled 



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