Jakuaet 20, 1911] 



SCIENCE 



99 



eral places and many contributions to the 

 subject may be expected within the next 

 decade. 



The plan for work upon the problems of 

 special interest in connection with the De- 

 partment of Botanical Research of the 

 Carnegie Institution of Washington, im- 

 plies the establishment of experimental 

 cultures in localities which furnish distinct 

 types of climate or which have character- 

 istic congeries of meteoric factors, as indi- 

 cated by the vegetation indigenous to them. 

 Secondly, these localities have been chosen 

 with regard to their geographical relations 

 so far as possible, in order that the possible 

 and probable fate of migrating species 

 might be studied. The behavior of plants 

 in these localities is recorded as to anatom- 

 ical alteration and physiological departure. 

 Having detected some such feature of ap- 

 parent importance, its reappearance in 

 plants from seeds carried to the original 

 habitat and other locations is followed as 

 one line of evaluation. Contemporane- 

 ously, the form is taken into the laboratory 

 and here by analytical experimental tests 

 the effort is made to ascertain to what 

 special agencies the departures are due. 

 Such determination of the identity of ex- 

 citing agencies has been made by Stockard, 

 who found that the cyclopean embryos of 

 Fundulus occurring in nature could be in- 

 duced by the action of magnesium salts 

 introduced into the sea-water containing 

 the eggs. 



Our increased insight into the nature of 

 natural groups of organisms has shown the 

 necessity and suggested the means of ob- 

 serving certain distinctions and precau- 

 tions in this work. Thus it is of the great- 

 est importance that the living material 

 shall be shown to be either simple geno- 

 types or that its phsenotypic nature be ap- 

 prehended in order that the integration 

 and combination of these forms shall not 



be mistaken for environic effects. When a 

 lot of plants is taken from one plantation 

 to another, data of the original locality are 

 preserved, as the stand of the plant in that 

 place serves as the control. If the plant is 

 multiplied vegetatively in the test, it 

 might reveal a possible complex character 

 of the material in bud sports, but other 

 divergencies might be well ascribed to local 

 effects. On the other hand, if introduced 

 in the form of seeds, the possible complex 

 character of the material would soon be- 

 come apparent, especially if the genera- 

 tions were followed properly. In the 

 actual management of the cultures, it is 

 found profitable to reintroduce forms from 

 the original or control lot of various 

 species in order to follow the first stages of 

 their adjustment repeatedly. 



The genetic character of environic ef- 

 fects remains to be considered. In any 

 species or genotype there is, withal, a 

 limited number of things included within 

 the morphological possibilities. The ap- 

 pearance of any character in an acclimati- 

 zation culture raises a question at once as 

 to the standing of the new feature. Is it a 

 regressive character, once displayed by the 

 species and now recalled, or is it to be con- 

 sidered as a character de novo, arising 

 simply and directly in response to the ex- 

 ternal agencies which have been seen to 

 induce it ? Thus our general knowledge of 

 the Cactaceas leads us to assert with some 

 confidence that the reappearance of a full 

 complement of spines in a prickly pear, 

 from which they had all but disappeared, 

 is a regression or return to the condition of 

 the greater majority of the group, a condi- 

 tion which must have been shared by its 

 ancestors at no remote stage in its progres- 

 sive development. 



None of the attempts hitherto made to 

 perfect a theoretical conception which 

 would be useful in interpreting the mech- 



