1 74 SUPPLEMENT TO 



rising from the acid might be noted. Similar seeds 

 were sown at the same time and in the same way, 

 but without the acid, so as to permit of comparison. 

 These experiments have afforded some interesting 

 results,* but do not supply any positive data which 

 might help us to discover the secret of the ants. 

 They narrow, indeed, the area in which search can 

 profitably be made, indicating as they do that the 

 vapour of formic acid is incapable of rendering the 

 seeds dormant after the manner of the ants, and 

 showing, on the contrary, that its influence is always 

 injurious to the seeds, even when present only in 

 excessively minute quantities. 



It appears to me now that the most promising 

 field for experiments made with a view to clearing up 

 this difficulty, is that afforded by the closer investi- 

 gation of the phenomena of normal germination, and 

 by a study of the conditions under which seeds 

 remain dormant, as they are occasionally known to 

 do, in situations which our general experience would 

 have selected as favourable to germination. 



I have good hopes, also, that when we come 

 to know more of the habits of harvesting ants in 

 tropical countries, and when naturalists have exca- 

 vated and described their subterranean stores — a thing 

 which has not yet been done as far as I know — 

 we may gather fresh indications to guide us in our 

 search. 



I am puzzled to account for the fact, which I have 

 seen stated by more than one observer in India, that 



* I hope shortly to offer these observations, together with another series of a 

 similar nature in which my friend Mr. J. B. Andrews has taken part, to the 

 Linnean Society. 



