September 17, 1908J 



NA TURE 



489 



society of Papers, by Darwin and Wallace, which 

 revolutionised the whole of Biology. There can svnely 

 liave been few occasions when the commemoration of the 

 jubilee of an epoch-making discovery has been attended 

 by the man whose work was thus recognised. I am sure 

 that I am expressing a unanimous feeling in saying that 

 the award of the first Darwin-Wallace medal on that 

 occasion to Mr. Wallace in person was a source of deep 

 graiilication to all men of science, and that the presence 

 at the same meeting of others whom all Biologists must 

 regard with peculiar respect gave the occasion a perfectly 

 unique character. 



The present century has seen a remarkable development 

 of the study of the problems of heredity and variation, 

 largely as the result of the interest awakened in the 

 resuscitation of Mendel's experimental work from the 

 oblivion in which it had remained for so many years, 

 though the general problem is being attacked concurrently 

 by investigators who attach more importance to the statis- 

 tical method of study. Prof. Bateson, who has given the 

 name " Genetics " to the experimental study of heredity, 

 chose the advances made in that branch of Biology up to 

 1904 as the subject of his able address to Section \i in 

 that year. .Some of the more recent conclusions of the 

 workers in Genetics are to be discussed by this Section 

 during the present meeting. It cannot be doubted that 

 an accurate knowledge of the principles of heredity is 

 destined to exert a marked influence on the practical 

 concerns of humanity. 



The study of diseases which are due to parasitic Protozoa 

 has made striking progress during the last few years. 

 Protozoology has become a distinct branch of Zoology, 

 represented by its own journals and its own professors 

 and lecturers, while it can command the resources of the 

 schools of tropical medicine where researches are being 

 carried on from which great benefits to humanity may be 

 anticipated. Malaria, sleeping sickness, yellow fever, and 

 the numerous diseases of domestic animals due to parasitic 

 Protozoa such as Trypanosoma, Spirochsta, and Piro- 

 plasma, are some of the complaints which are now recog- 

 nised as the objects of Zoological study. Most of these 

 diseases are transmitted by blood-sucking Insects and 

 .Arachnids, an accurate knowledge of which has become a 

 matter of pressing practical importance. 



Ihe history of Protozoology affords a complete vindica- 

 tion of the importance, even from a utilitarian standpoint, 

 of conducting scientific investigations for their own sake, 

 even though the likelihood that they will ever have any 

 practical bearing may not at first be apparent. Some years 

 ago it would have been generally supposed that the study 

 of Ticks was a case of this kind, and that it could at 

 most be of interest to the special students of the .Arachnida. 

 How far such a view would have been from the truth is 

 well known, but we are suffering now from the com- 

 parative neglect of this group of animals in the past. 

 There is still no satisfactory monograph by the aid of 

 which the species of Ticks can be discriminated, and there 

 ar." few Zoologists who would be prepared to express an 

 opinion with regard to the determination of even those 

 species that are the commonest and the most injurious. 

 While it is clear that the investigation of the Arthropod 

 carriers of parasitic Protozoa is essentially a Zoological 

 question, it is equally true that the elucidation of the 

 parasites themselves is largely dependent on the results 

 that have been achieved by Zoological investigators who 

 have worked without any thought of a practical outcome. 

 The late Prof. Schaudinn, to whom we owe so manv 

 brilliant results in the study of the Protozoa, commenced 

 his investigations from the Zoological side, and continued 

 them in their applications to preventive medicine. It is 

 generally admitted that the study of many of the tropical 

 diseases can only be carried on by means of a due co- 

 orditiation between Zoological and Medical' methods of 

 inquirv. 



As a further instance of the manner in which Biological 

 science_ may react on other studies, I may mention the 

 interesting theory which has recentlv been developed bv 

 Mr. W. H. S. Jones,' to the effect that the decay of the 



J "Malnria: A Negli-cted Factor in the History of Greece and Rome." 

 (Cambridge : IJowes and Eowes, 1907.) 



NO. 2029, VOL. 78] 



ancient civilisations of Greece and Rome was largely due 

 to the introduction of malaria into those countries. 



I can do no more than allude to Economic Entomology, 

 a subject which has at present received but little official 

 support in our own country, although its importance is 

 fully recognised abroad, particularly in the United States 

 of America, where large organisations are devoted to the 

 combat with the Insect enemies of agriculture. We are 

 fortunately spared some of the worst of the foes of vegeta- 

 tion which devastate other lands. But many of our 

 cultivated plants suffer severely from the ravages of Insects 

 and Arachnids ; and it is perhaps not too much to hope that 

 more systematic measures will some day be taken in this 

 country to disseminate the knowledge by which this injury 

 to agriculture may be minimised. 



As a last illustration of the way in which Zoology comes 

 into relation with practical matters, I may allude to the 

 question of fishery investigation. Although much remains 

 to be done in this connection, the importance of purely 

 scientific work has been to some extent officially recog- 

 nised. The Board of .Agriculture and Fisheries in England, 

 the Scottish Fishery Board, the Fisheries Branch of the 

 Department of Agriculture and Technical Instruction for 

 Ireland, and other organisations which are mainly or 

 entirely supported by private funds, are in part devoted 

 to the interests of the fishing industry. The Government 

 has latterly participated in an international investigation 

 of the North Sea, as the result of which many interesting 

 facts have been recorded with regard to the life-histories 

 of food-fishes, their migrations at various periods of life, 

 the age at which they become sexually mature, and the 

 nature of their food. These are questions that demand 

 study by experienced Zoologists ; and the interrelations of 

 food-fishes and the organisms on which they subsist or 

 with which they come into competition are so complex 

 tliat a full study of the entire marine fauna appears to 

 be a necessary preliminary to the elucidation of the ques- 

 tions of immediate practical utility. 



I have tried to indicate that Zoology is a subject that 

 has important relations with the practical concerns of man- 

 kind. But in Zoology, as in other branches of science, 

 the principal advances have been made by investigators 

 who have studied it for its own sake, without thought of 

 the practical outcome. It would undoubtedly be a mis- 

 fortune should an entirely utilitarian spirit become 

 dominant in the pursuit of science. In the full conviction 

 of the truth of this statement I venture to invite your 

 attention to certain questions connected with the Polyzoa 

 — a somewhat neglected group of animals which I do not 

 profess to be able to connect in any direct w^ay with prac- 

 tical matters. In choosing this subject I have been in- 

 fluenced by the belief that it is well for the President of 

 a Section to speak on matters of which he has had prac- 

 tical experience. 



During the course of my studies on the Polyzoa I have 

 been conscious of the existence of many unsolved problems 

 and difficulties, some of which are connected with the func- 

 tions, distribution, and variations of certain remarkable 

 appendages known as " avicularia " and " vibracula.'* 

 Although the facts bearing on the significance of these 

 organs are familiar to specialists only, they appear to me 

 capable of throwing light on questions of general Biological 

 interest, particularly in connection with variation in animals 

 that increase by budding. 



The statement has often been made, as the result of a 

 theoretical conception of the physical basis of heredity, that 

 the asexual method of reproduction gives rise to little or 

 no variability. Although there are many reasons for 

 doubting the validity of this conclusion, it may be well to 

 state at the outset that the Polyzoa, which are without 

 exception characterised by increasing in an asexual manner, 

 show a high degree of variability in the individuals thus 

 produced. So much is this the case that the want of 

 fixitv of type which results from the tendency to vary 

 renders the definition of species particularly diflficult in this 

 group of animals. 



Meeting as we do at Dublin, there is a special appro- 

 priateness in discussing the Polyzoa, as a tribute to the 

 memory of a distinguished Irish naturalist, J. V. Thomp- 

 son, to whom we owe not only the name Polyzoa, but also 

 the first clear conception of what these animals really are. 



