June 10, 1904.] 



SCIENCE. 



881 



tures, such as galls, and supposedly bene- 

 ficial structures, such as aer.enchyma of 

 water plants, undifferentiated mesophyll 

 of shade plants, etc. That all biologists 

 are not going the way of Klebs and Mor- 

 gan is evidenced by Francis Darwin's re- 

 view of Klebs 's book ; Darwin holds that in 

 the development of structures, adaptive- 

 ness must be taken into account, and that 

 there is a difference between the organic 

 and the inorganic. Verworn's biogen 

 hypothesis and Driesch's neo-vitalism are 

 expressions of a supposed difference be- 

 tween the living and non-living. 



Nordhausen's experiments seem to sup- 

 port the Lamarekian theory, since he finds 

 that the structural characters of shade 

 leaves of the beech remain in large part in 

 changed conditions. Thus useful charac- 

 ters, originally acquired through the agency 

 of external factors, may be transmitted, at 

 least in part, to later generations. On the 

 other hand, the Lamarekian idea seems not 

 to be supported by the work of Wieders- 

 heim and Ball, who failed to confirm 

 Hegler in the matter of securing an in- 

 creased development of mechanical tissue 

 in growing plants subjected to tension. 

 Potonie has attempted to attack the prob- 

 lem from another side by a study of fossil 

 plants ; he claims that carboniferous plants 

 were less perfectly adapted than those of 

 to-day. This, however, is denied by Wes- 

 termaier, who thinks that organisms must 

 always have been as well adapted as they 

 are now. Whatever the final outcome con- 

 cerning this fundamental problem, whether 

 the study of adaptation is scientific or un- 

 scientific, it is of value to recognize the 

 presence of the problem; many have taken 

 for granted on one side or the other what 

 ought to be a subject for profound investi- 

 gation. 



Ganong in his splendid paper concerning 

 the Bay of Fundy marshes has expressed 

 another respect in which past study has 



been at fault, viz., in devoting paramount 

 attention to structural rather than physio- 

 logical characteristics of plants. We need 

 to know not only about root hairs, leaf 

 shapes and development of so-called pro- 

 tective structures; it is far more impor- 

 tant to know a plant's physiological 

 adaptation; its transpiration, its water-ab- 

 sorbing power, its physiological plasticity. 

 From the hasty presentation here given it 

 might be inferred that Lamarckians and 

 Darwinians are necessarily regarded as be- 

 lievers in adaptiveness as a factor in evolu- 

 tion, and mutationists are necessarily sup- 

 posed to hold the opposite view. This is, 

 of course, incorrect, but it is certainly true 

 that those who hold to mutation have laid 

 the least stress upon the significance of 

 adaptation. To the speaker it seems as if 

 all three theories of evolution, and perhaps 

 others yet unborn, are quite tenable, and 

 that the problem of adaptation is not neces- 

 sarily to be associated with any particular 

 theory of evolution. 



Not all will admit that experimental 

 morphology is a part of ecology, but that 

 its results are of the utmost importance 

 in ecological interpretation can not be de- 

 nied. The works of Klebs and Kiister, to 

 which allusion has been previously made, 

 take a foremost place in this field, but in 

 a summary of this character it will be im- 

 possible to specify details. Among the 

 more interesting of recent experiments we 

 may cite some which deal with the phe- 

 nomena of symbiosis. Bernard's theory 

 that tubers are essentially galls due to 

 fungal attacks has been disputed by Laur- 

 ent, who shows that concentrated solutions 

 also induce tuberization. Bernard repeats 

 and confirms the work of Laurent, and as 

 a consequence broadens his view as follows : 

 tuberization is induced by factors which 

 cause a greater osmotic pressure within the 

 cell. In nature fungi which penetrate the 

 growing tissues form the chief means of 



