212 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY. 



The comparison between Peas and Haricots is a very 

 marked one. Haricots are killed by one to two days 

 immersion in absolute alcohol ; by one day's immersion 

 in 50 p. c. alcohol or an aqueous solution of HgCl 2 ; they 

 can withstand immersion in water for 5 days without 

 apparent injury but they are killed by 10 days immersion 

 in water. 



It must be remembered that these two plants belong to 

 allied genera of the same natural order, the seeds being of 

 the same type and the protective integuments of about 

 equal thickness. A close comparison between these seeds 

 should therefore afford instructive data for estimating the 

 relative value of the different factors concerned in promot- 

 ing and preserving the vitality of the seed. The following 

 table gives the effects of an aqueous solution of HgCl 2 on 

 Peas and Haricots, the seeds being planted direct after 

 washing and also after one day's subsequent soaking in 

 water to remove excess of the salt more perfectly. 





Haricots 1 day. 



Peas 1 day. 



Peas 2 days. 



Peas 3 days 



Aqueous Solution 

 HgCL, 



None. 



None. 



None. 



None. 



Ditto after soak- 

 ing in water for 

 1 day. 



None. 



8 p.c. germinated. 



5 p.c. germinated. 



None. 



Similar seeds were after one and two days immersion 

 soaked in water for a day and then treated with ammon- 

 ium sulphide. This reagent throws down a black precip- 

 itate of mercuric sulphide and hence all parts of the seeds 

 into which the mercury salt has penetrated turn black. 

 The seeds before treatment with the ammonium sulphide 

 are sliced in halves so as to divide the embryo proper 

 longitudinally and thus the exact distance which the salt 

 has penetrated into both radicle and plumule can be 



