SLUGS AS MYCOPHAGISTS 231 



slug had disappeared. In all probability the slug had returned to 

 the border whence it had originally come. 



Experiment VI. The next evening, September 11, I set out 

 upon the gravel the same three heaps of fruit-bodies as had been 

 used the night before (Fig. 82, no. VI). Again the heaps were made 

 in a row parallel to the edge of the border, the intervals between 

 the heaps being 4 feet, the Boletus scaber heap occupying the central 

 position in the row and the Cortinarius caninus and Russula nigricans 

 heaps the end positions. However, the arrangement of the heaps 

 differed from that of the night before in that each heap instead of 

 being only 12 feet from the edge of the border was now 20 feet. 

 The condition of the Russula nigricans and Cortinarius caninus 

 fruit-bodies was still good, but the Boletus scaber fruit-bodies were 

 now in an advanced stage of putrescence. The evil state of the 

 Boletus scaber fruit-bodies was perhaps the reason why, as we shall 

 see in the sequel, they were not visited by a slug in this particular 

 experiment. The night was again very dark and still. At 9.40 P.M., 

 with the help of a lighted taper, I found a Limax maximus which had 

 just emerged from its hiding-place and which was moving behind 

 a block of sandstone in the border 21 feet from the fungi. At 

 11 P.M. I went out again and found that the slug had already 

 travelled 11 feet upon the gravel toward the fungi from which it 

 was now only 9 feet distant. I watched the slug for a little time 

 but, being afraid of disturbing it too much, soon retired into the 

 house. At 12 P.M. I sought the slug again and found it 6-5 feet 

 away from the row of fungi ; but, to my surprise, it was moving 

 away from the row of fungi instead of toward it. At 1 A.M., the 

 slug was 5 feet away from each of the heaps of Boletus scaber and 

 of Russula nigricans ; at 1.30 A.M., about 2 feet away ; and, finally, 

 at 2 A.M., actually upon one of the fruit-bodies of Russula nigricans 

 devouring the gills . Thus the slug, after some five hours of wandering, 

 had at last succeeded in finding one of the heaps of fungi set 20 feet 

 from the edge of the border where the slug had first been seen. 



The slug, between 9.40 P.M. and 11 P.M., must have travelled 

 almost directly toward the fungi ; for, during this period, it 

 traversed 1 foot of border and 11 feet of gravel in the direct line of 

 its journey. But between 11 P.M. and 1 A.M. this rapid progress 



