210 Alfred J. Eivart: 



!iir-drie/d uerniinable seeds are probably the result of surface 

 oxidation in the integument, and hence arises the fact that ex- 

 posure to litrht increased these (gaseous exchanges instead of 

 slightly decreasing them, as in true respiration. In addition no 

 precautions appear to have been taken to ensure the absence of 

 adhering micro-organisms. 



Becquerel's conclusions that the impermeability of the coats of 

 macrobiotic seeds is the gradual result of their ageing, and that 

 only seeds with impermeable coats can last for any length cf time 

 have already been shown to be incorrect. The impermeability is 

 due to the pre'sence of a cuticle developed during ripening, and 

 the presence or absence of the latter determines whether a seed 

 will or will not have a long life in the soil, but not whether it 

 will have a long life when preserved in dry air. Macrobiosis is 

 the result of a biological adaptation of the protoplasm, in which 

 an impermeable cuticle plays a merely accessory or aiding part. 



In regard to the impermeability of the integuments of seeds to 

 absolute alcohol, Becquerel has overlooked the fact that the first 

 observation (on Cress seeds) is due to de Bary, and that this 

 question was investigated by me with some completeness in the 

 Trans. Liverpool Biol. Soc. 189i, pp. 207-247, in which paper 

 an explanation is given of the fact that diluted alcohol is more 

 fatal to dry seeds than absolute alcohol. 



Hiltner and Kinzel (Zentrbl. Agr. Chem. 36, 1907, pp. 381-4) 

 find that the hardness of the seeds of Clover and other Legn- 

 minosao increases when they are subjected to moderate dry heat, 

 and hence they conclude that the conditions during ripening de- 

 termine the percentage of hard seed. It is only to be expected 

 that when the " hardness " is due to the presence of a cuticle, 

 xerojihilous conditions should exercise the same influence on the 

 development of cuticle on ripening seeds as on leaves and other 

 parts, but the partial hardening of ripe seeds when subjected to 

 dry heat is probably of dissimilar origin. 



In conclusion, I have to thank Messrs. Tovey and Audas. of 

 the National Herbarium, for their zealous co-operation in the 

 search for material, in verifj'ing the name?, and in the convction 

 of proofs. The tedious process of seed counting was largely 

 carried out by Messrs. O'Brien and Cronin, of the l^otanical 

 Department of the Universit3^ 



