SEEDLINGS, FOODSTORES AND GERMINATION. 79 



curious glossy shell produced by the enlarged bract of 

 Job's Tears {^Coix lachryma) is as hard as opal, and the 

 shell (carpel) of Lithospermum is of the same degree of 

 hardness as Fluorite. More observations on this subject 

 would be interesting. 



The pressure which seeds are able to support without 

 breaking is sometimes astonishingly great. The follow- 

 ing were the results obtained by the writer. The tests 

 were carried out by means of a Salter's Spring balance. 

 The seeds or fruits were placed upon it between glass 

 slides and pressure exerted until they cracked ; only 

 cases in which the moment of breaking could be dis- 

 tinctly perceived were allowed to count. The first 

 column shows the number of each kind which were 

 tested, the second the lowest, and the third column the 

 highest weight, which was found to produce breaking. 

 The last column gives the average breaking weight. 



