president's address. 65 



The experimental method has already achieved much, and in our 

 own department signs are forthcoming of useful and suggestive 

 results. Thus, in the year 1890 our energetic well-wisher Professor 

 "W. A. Herdman, as the result of some pi'eliminary experiments on the 

 periwinkle {Littorina rucUs), was led to the conclusion,^ which had been 

 already foreshadowed by Jeffreys, that that animal may be becoming 

 adapted to a terrestrial existence. Again, H. de Varigny, repeating 

 the observations of Semper upon the growth of Lirnncea, has shown,- 

 from an elaboi-ate series of experiments — varying the temperature, food 

 supply, the access of air, the volume of water, and, above all, the 

 limits of movement and the numbers of his colonies — that there is no 

 reason for concluding that the favourable influences of a large volume 

 of water are here due to the presence of chemical agents favourable to 

 growth ; but that, conversely, the retardation in growth would appear 

 to be directly related to limitation of activity and power of movement. 

 What a field lies before him who will continue the study of this 

 plastic genus ! 



When, in addition to tliis, we reflect that in the so-called Physa 

 lamellata of Madagascar, as Paul Pelseneer has successfully proved,^ 

 we have to deal with a Pulmonate which, in secondary adaptation to 

 aquatic life, has developed a tegumental "gill" morphologically distinct 

 from the ctenidium ; that in Planorhis corneus and P. marginatus a 

 similar tegumental lobe is present ; that in Ajicylus this same secondary 

 adaptation has led up to the suppression of the lv;ng-sac ; that from 

 the folds of the adhering Chiton air as well as water may be 

 displaced on handling ; and that Simroth has just recorded from 

 the Tenimber Islands ^ a Chiton [Acanthopleura spiniger ?) which 

 would appear to have developed a pulmonary organ of respiration, 

 our interest in experimental inquiry as it may relate to the 

 environment and changed conditions of life is aroused to the utmo.st. 

 If such things have come about in the course of time, and can be 

 established by actual manipulation, who knows what may not 

 await the patient experimentalist of the future. In its bearings on 

 the conditions of local distribution in shallow water, on bathymetric 

 extension, and specific variation as related to these influences, the 

 experimental method appears to me to give promise of most important 

 results in Malacology. Just as the physiological graduates off into the 

 pathological, the full significance of many a healthy or a diseased 

 state becoming intelligible only on a knowledge of its opposite, so, in 

 the hands of the experimentalist, the normal phenomena of animal 

 life will most assuredly, in coui'se of time, become illumined by 

 prolonged and careful study of the organism under changed conditions. 

 And from all that is now going forward, it is plain that the pathologist 

 holds the key to the solution of many a life problem. 



' Herdman, Rep. Liverpool Mar. Biol. Sta. Liverpool, 1890, p. 17. 



^ Journ. Anat. Phys. Paris, torn, xxx, p. 147. 



2 Comptes Reud. Acad. Sci. Paris, torn, cxix, p. 354. 



* H. Simroth, Sitzb. Naturf. Gesellsch. Leipzig, Jlig. 19-21, 1895, p. 106. 



