September 16, 1898.] 



SCIENCE. 



355 



as leptocephalus brevirostris being the 

 young of our common fresh-water eel. 

 When it gets to the length of about an inch 

 it changes into one of the tiny eels known 

 as elvers, which swarm in thousands up 

 our rivers. Thus the habits of the eel re- 

 verse those of the salmon. I must not, 

 however, go into detail, but I will take one 

 other case— the fly of the King Charles oak- 

 apple, so familiar to every schoolboy. In 

 this case the females are very common ; the 

 eggs were known. But no on6 had ever 

 seen a male. Hartig in 1843 knew 28 

 species of cynips, but in 28 years' collecting 

 had never seen a male of any of them. 

 Adler, however, made the remarkable dis- 

 covery that the galls produced by these 

 females are quite unlike the galls from 

 which they were themselves reared; that 

 these galls produced flies which had been 

 referred to a distinct genus and of which 

 both males and females were known. Thus 

 the gall flies from the King Charles oak- 

 apple (which are all female) creep down 

 and produce galls on the root of the oak, 

 from which quite a dissimilar insect is pro- 

 duced, of which both sexes occur, and the 

 female of which again produces the King 

 Charles oakapple. This is not the oppor- 

 tunity to go into details, and I merely 

 mention this as another illustration of the 

 surprises which await us even in the life 

 history of our commonest species. 



Many writers have attributed to animals 

 a so-called sense of direction. Ihaveshown 

 that some species of ants and bees have 

 none. Pigeons are often quoted, but the 

 annals of pigeon-flying seem to prove the 

 opposite. They were jumped, as it were, 

 from one point to another. We know little 

 about our own senses — how we see and hear, 

 taste or smell, and naturally even less 

 about those of other animals. They are no 

 doubt in some cases much acuter than ours, 

 and have different limits. Animals cer- 

 tainly hear sounds which are beyond the 



range of our ears. I have shown that they 

 perceive the utraviolet rays, which are in- 

 visible to us. As white light consists of a 

 combination of the primary colors this sug- 

 gests interesting color problems. Many 

 animals possess organs apparently of sense 

 and richly supplied with nerves which yet 

 appear to have no relation to any sense 

 known to us. Thej' perceive sounds which 

 are inaudible to us ; they see sights which 

 are not visible to us ; they, perhaps, possess 

 sensations of which we have no conceptions. 

 The familiar world which surrounds us 

 must be a totally different place to other 

 animals. To them it may be full of music 

 which we cannot hear, of color which we 

 cannot see, of sensations which we cannot 

 conceive. There is still much difl^ei'ence of 

 opinion as to the mental condition of 

 animals, and some high authorities regard 

 them as mere exquisite automata, a view to 

 which I have never been able to reconcile 

 myself. The relations of different classes 

 to one another, the origin of the great 

 groups, the past history of our own ances- 

 tors, and a hundred other problems — many 

 of extreme practical importance — remain 

 unsolved. We are, in fact, only on the 

 threshold of the temple of science. As re- 

 gards these profound problems animals are 

 even more instructive than plants. Ours 

 is, therefore, a delightful and inspiring sci- 

 ence. 



We are fortunate in meeting in the an- 

 cient University of Cambridge, a visit to 

 which is under any circumstances delight- 

 ful in itself from its historic associations, 

 the picturesque beauty of the buildings, 

 and as the seat of a great zoological school 

 under our distinguished colleague Professor 

 M. Foster. 



At the close of the presidential address, 

 which was warmly received, the Vice- 

 Chancellor, Dr. Hill, welcomed the Congress 

 on behalf of the University. Greetings were 

 presented by representatives of foreign na- 



