952 



SCIENCE. 



[N. S. Vol. XXIII. No. 599. 



it has once begun, and thus a permanent 

 change is brought about. If we consider this, 

 then the objection that sometimes the changes 

 of the organisms have disappeared after the 

 normal conditions had been reestablished, does 

 not hold good ; in fact, this was to be expected 

 (compare Naegeli'a experiments with Hier- 

 acium; also de Vries's experiments furnish 



This way of looking upon the 'pressure of 

 environment,' as producing a certain tendency 

 to vary in a definite direction, easily explains 

 it that we have evidence of definite variation. 

 M. M. Metcalf is inclined to believe that 

 such instances are in favor of the assumption 

 of the action of inner causes; but I do not see 

 why this should be so. A repeated or constant 

 action of the same external stimulus should 

 produce in any organic form the tendency to 

 react upon this stimulus in a definite way. 

 This has been called orthogenesis by Eimer. 

 Such cases are known, and I do not hesitate 

 to attribute them to a permanent action of the 

 same external force upon a multitude of indi- 

 viduals. Of course, as soon as this process is 

 well started, inheritance begins also to play a 

 part, and it is this latter factor that finally 

 firmly establishes the new characters. 



As to the value of experiments in the study 

 of variation, I want to call attention to the 

 difficulty in interpreting the facts, when such 

 experiments are made under artificial and 

 unnatural conditions, as, for instance, in the 

 botanical garden, or with domesticated forms. 

 Here it is apparent that such a complexity 

 prevails, not only a few, but a large number 

 of conditions being different from those in 

 nature, that the experiment becomes a be- 

 wildering maze. In my opinion, experiments 

 should be made in close touch with nature, 

 changing, if possible, only one or a few of the 

 conditions, so that we may be able to record 

 the effects of each single changed factor in 

 the environment. But I do not believe that 

 this is an easy task. On the other hand, we 

 should bear in mind that nature has made and 

 is making these experiments for us: the proc- 

 ess of variation is going on continuously, and 



" Science, May 18, 1906, p. 787. 



the effects of former variation are seen in 

 nature, and may be studied in the shape of 

 the actually existing variations, varieties and 

 species, and their relation to the environment 

 (ecology). This work naturally falls within 

 the scope of the systematist, and is largely 

 field work; specimens of this kind of work 

 have been furnished by Merriam, Allen and 

 others, and the modem ecological researches 

 are just what is wanted. But we must con- 

 fess that so far we have only the beginning 

 of this study, which should be encouraged and 

 enlaiged. For ecology teaches us what the 

 different types of environment are, and how 

 the different elements in the environment af- 

 fect each other, and how changes of environ- 

 ment may effect changes in the organization 

 of the different forms of life dependent on it. 

 A. E. Ortmann. 

 Caknegie Museum, Pittsbubg, Pa., 

 May 28, 1906. 



SPECIAL ARTICLES. 

 CORPUSCULAR RADIATION FROM COSMICAL SOURCES. 



In my address ' before the Physical Society, 

 I gave an account of observations made sev- 

 eral times daily since May 9, 1905, in a search 

 for the possible occurrence of an ultra- 

 mundane radiation. The work was there 

 , summarized as follows : 



Using the most sensitive condensation method, 

 i. e., that depending on the depression of the 

 limiting asymptote of non-energized, kiust-free 

 air, no change of the quality of scrupulously 

 filtered atmospheric air has thus far been de- 

 tected. * * * Naturally (ions) would vanish 

 during the slow passage of air through the filter, 

 but fresh ions should be reproduced within the 

 fog chamber by the same agency which generates 

 them without * * *. Probably, therefore, the 

 coronal method is as yet inadequately sensitive 

 to cope with the variations of the small nuclea- 

 tions specified. 



The ions, which are relatively large nuclei, 

 withdraw much of the available moisture 

 which would otherwise be precipitated on the 

 colloidal nuclei of dust-free air. Hence the 

 size of the terminal corona is diminished. 



' Physical Revieio, XXII., p. 105, 1905 ; also 

 p. 109 on ' radiant fields.' 



