Notes on Recent Literature. 
32 
Cassia bicapsularis ; 87 years old, 3 out of 10. 
Cytisus biflorus; 84 years old, 2 out of 10. 
Stachys nepetaefolia ; 77 years old, 1 out of 10. 
Trifolium arvense ; 68 years old, 2 out of 10. 
Ervum Lens ; 65 years old, 1 out of 10. 
Lavatera pseudo-OIbia ; 64 years old, 2 out of 10. 
Nelumbium codophyllum ; 56 years old, 4 out of 5. 
Nelumbium asperifolium ; 48 years old, 4 out of 5. 
Becquerel was able to make a significant generalisation about 
the type of seed that shows such considerable longevity: he 
observed that in all cases these seeds had exceptionally strong and 
impermeable integuments. 
Ewart’s paper contains a list of over 4,000 cases. About 3,000 
are his own observations (many are duplicates) and the rest 
(including Becquerel’s) are drawn from botanical literature. The 
number of seeds tested in each case and the percentage of successes 
is always recorded by Ewart: this latter is probably a point of some 
significance. His own observations were made mostly on a store of 
seeds of 600 species which he discovered locked up in a cupboard 
in Melbourne, and which had been sent out from Kew in 1856 for 
a projected botanic garden in Melbourne’, but never used. 
Here again it was found that the Leguminosse furnished more 
than half the number of cases of great longevity. In most of these 
the seeds are what is technically known as “ hard ” seeds, that is 
seeds which do not swell up when put in water. 
In a number of species of Leguminosae the seeds are provided 
with a particularly thick and resistant waterproof cuticle, and such 
seeds can only imbibe water when the continuity of this cuticle is 
broken. Becquerel took the precaution to break off a portion of the 
integument in his tests, and Ewart removed it by soaking the seeds 
for fifteen to ninety minutes in concentrated H 2 S0 4 which is 
then neutralised and washed away, whereupon the seeds swell 
readily. As an appendix to Ewart’s work Miss White verified the 
presence of this resistant cuticle by microscopic examination 
(drawings are given) and determined that the time of soaking in acid 
required was in proportion to its thickness. The seed of Adansonia 
Gregorii furnishes an extreme case and sometimes requires more 
than six hours in sulphuric acid to remove its cuticle. 
The fact that seeds thus hermetically sealed show the greatest 
longevity suggests that protection from some external influence is a 
factor in the preservation of viability. 
Becquerel established the further interesting point that not only 
are these “hard” integuments impervious to air, but that the dry 
testa of an ordinary pea or bean is also quite air-proof. He 
demonstrated this by fitting up detached pieces to close the top of 
the tube of a Torricellian vacuum, and he found that no air was 
sucked through the testa even in many months : the micropyle even 
is naturally hermetically sealed in some way and allows no air to 
pass. However, if the air in contact with the piece of testa is 
saturated with water vapour, then the testa slowly absorbs water 
and presently begins to allow air to pass by diffusion. As these 
phenomena hold with uncuticularised integuments it is concluded 
that pure cellulose walls are impervious to air when completely 
dried. 
