114 The Carnivora. 
lian scrubs I observed my retriever vigorously anointing 
himself after the manner of his kind, and on going to the 
spot found that he was rolling on a clump of living fungi 
which emitted a particularly evil smell. The large propor- 
tion of nitrogen, however, in fungi may give them a scent 
similar to that of animal matter. Dogs will go long dis- 
tances to a particular place, day after day, to thus indulge 
themselves. I have sometimes thought that the ammonia 
evolved during putrescence may be in some way pleasing to 
them, as there is reason to believe that it is in other circum- 
stances; but when I have saturated blotting paper with a 
weak solution of ammonia, and placed it before them, they 
have turned from it with indications of dislike. I have not 
formed any definite theory of the origin of this habit, 
though there has always been floating in my mind a suspicion, 
unsupported it must be confessed by any direct evidence 
of its possible association with the reproductive instincts. 
In his work on “Mental Evolution in Animals,” Dr. G. J. 
Romanes shows that he has considered it from the point of 
view of inheritance, and, since the laws of transmission of 
mental phenomena are now—thanks to the works of that 
writer and of Sir John Lubbock, and others who have enlarged 
on and ably illustrated Darwin’s doctrines—so much better 
understood than formerly, much new light has been thrown 
on obscure instincts. Mr. Hugh Dalziel writes to me on 
this subject: “At one time I thought, or rather wondered, 
whether the habit of rolling in carrion and other decayed 
animal matter had originated as a means employed to enable 
dogs to trace each other, just as micturition appears to serve 
that purpose. After reading Romanes’ book I became con- 
firmed in an opinion that had been growing with me, that, 
taste and smell being closely allied senses, rolling in carrion 
is an inherited habit, causing pleasurable sensations from 
association with the glorious feasts enjoyed on the battle- 
fields, and on the putrid carcases of animals, for which 
dogs, when unrestrained, still often display a strong relish.” 
