Loiif/^vity of Seeds. 411 



tissue is of interest because correlated with it, as already shown. 

 is a greater resistance to the action of sulphuric acid. 



The results obtained with Melilotu.s alba did not correspond 

 with any of the others on account of the different nature of 

 its seed coat. Boiling in absolute alcohol for five minutes 

 or for three-quarters of an liour in 70 per cent, methylated spirits 

 at 7-3 deg. C. produced swelling, but there was no apparent 

 change in the structure of the seed coat. The swelling must 

 have been due to the disturbance of the micellae of hemi- 

 cellulose by the action of heat causing the cuticularised cells to 

 become separated, and not to any actual change in the cuti- 

 cularised substance. Hemicellulose, being unaffected by chloro- 

 form, effectually prevented the latter from reaching and dis- 

 solving out the fats in the cuticularised wallis, and maceration 

 in chloroform at 30 deg. C. for eighteen weeks had no effect 

 whatever on the seeds. Sections were then made and kept in 

 chloroform at the same temperature for a period of four weeks, 

 and at the end of that time were washed and stained with 

 chor-zinc-iodine. The whole cell wall now showed the hemicellu- 

 lose colour, which was darker at the tip, where it had been pre- 

 viously cuticularised. (Plate 81 c.) The action of caustic potash 

 was to entirely remove the outer membrane and to take out, 

 probably by saponification, the waxy substances from the cuti- 

 cularised parts. 



In the case of Alhizzia h>j)hauihn some of the tests were made 

 with both old and new seed, and although the final results 

 were the same, the degree of resistance of the two samples 

 differed widely. For example, two haurs in boiling alcohol 

 caused 69 per cent, of the fresh seeds to swell, whereas three 

 hours were required to produce a similar result with the old 

 seed. As in all other cases the alcohol had no apparent effect 

 on the structure of the cuticularised parts. In using caustic 

 potash, four weeks at 30 deg. C. or one hour on a boiling water 

 bath were required to produce swelling. The seeds' coats were 

 softened to such a degree that section cutting was out of the 

 question, but parts mounted and stained with chlor-zinc-iodine 

 gave a distinct hemicellulose reaction. Maceration in chloroform 

 for 18 weeks at 30 deg. C. also produced swelling, and in pre- 

 pared sections the palisade cells which had previously stained 



