1SS0-1SS2] EARTHWORM 215 



sickly (probably with orms is thus hastened. I Letter 549 



will add a few words to what 1 have said about the e track 

 Occasionally worms suffer from epidemics (of what nature I 

 know not) and die by the million on the surface of th 



round. Your ruby paper answers capitally, but I suspect 

 that it is only for dimming the light, and i know not h< 

 illuminate worms by the same intensity of light, and yet of a 

 colour which permits the actinic rays to pas--. 1 have tried 

 drawing triangles of damp paper 1 through a small cylindrical 

 hole, as you suggested, and I can discover no source of error. 

 Nevertheless I am becoming more doubtful about the intel- 

 ligence of worms. The worst job is that they will do their 

 work in a slovenly manner when kept in pots,- and I am 

 beyond measure perplexed to judge h such observ 



ti. >ns are trustwi >rthy. 



To E. Ray Lankcster. i... rr .. , 



Mr. Lankcster had written Oct. nth, [881, to thank Mr. Darwin for 

 the present of the Earthworm book. lie a>ks whether Darwin know 

 of " any experiments on the influence of sea-water on earthworms. I 

 have assumed that it is fatal to them. But there is a littoral species 

 {Pontodrilus of Lerrier) found at Marseilles." Lankester adds, " It is 

 a great pleasure and source of pride to me to see my drawing of the 

 earthworm's alimentary canal figuring in your pages." 



i.?th [1881]. 



I have been much pleased and interested by your note. 

 I never actually tried sea-water, but I was very fond of 

 angling when a boy, and as I could not bear to see the worms 

 wriggling on the hook, 1 dipped them always first in salt 

 water, and this kilted them very quickly. I remember, though 

 not very distinctly, s< eing several earthworms dead on the beach 

 close to where a little brook entered, and I assumed that they 

 had been brought down by the brook, killed by the sea-water, 

 and cast on shore. With your skill and great knowledge, 

 I have no doubt thai y u will make out much new about the 

 anatomy of worms, whenc\ u take up the subject again. 



1 Triangles of paper were used in experiments to test the intelligence 

 of worms {loc. a'/., p. 83 >. 

 * Loc. cit., p. " 



