DEPARTMENT OF BOTANICAL RESEARCH. 83 



EVOLUTIONARY MOVEMENTS. 



Of the many activities of evolutionary import in these cultures at 

 Tucson, which duphcate as nearly as possible conditions of evolution 

 in nature, the chief and impressive result is that of a gradual continuous 

 change in the population in the direction forced by the habitat, result- 

 ing in alterations, with habitudinal adjustment or adaptation. These 

 changes in function and structure, some additions, others losses, 

 produce gradually altered aspects and behavior of the population, are 

 genetic and not somatic, and not reversible, as far as experience goes. 



Mutations also occur as the product of complex hybrid constitution, 

 of sharp incident external forces, and there may well be other methods 

 of origin of many mutant types, which may and do become progeni- 

 tors of specific isolated groups. Populations, apparently, do not change 

 suddenly, but rather by slow accommodation to changed conditions. 



Transmission or Recurrence of Environic Effects in Phytolacca, hy 



Francis E. Lloyd. 



The progeny (Fi) resulting from seeds developed by abnormal green 

 fruits of the "Tucson plant No. 1," which were reported upon while 

 they were still young last year, have now come to maturity, and have 

 produced inflorescences. These, though arrested by the climatic con- 

 ditions, developed far enough during the present season to show that 

 they are quite normal. The condition under examination, therefore, 

 appears not to be inherited. 



Plants (of lot No. 131) originating at Carmel, and normal as to 

 structure of floral parts, were grown in Tucson and there produced 

 abnormal inflorescences (see Year Book, 1915). An individual known 

 to have behaved thus in 1915 was returned to its original habitat at 

 Carmel in December 1915. It was gro\\ii under glass and produced 

 three shoots. One of these bore nonnal flowers and accompanying 

 structures, while the other two bore abnormal inflorescences. 



It is recalled that this abnormal condition was first shown b}^ the 

 "Tucson plant No. 1," grown in Tucson in 1913 by Dr. MacDougal. 

 The coincident occurrence of insect galls on this plant in 1914 suggested 

 the possibility of insect origin in explanation of all the abnormalities 

 observed. A shoot of this plant, protected against the approach of 

 insects during 1915 by a suitable screen, continued to produce 

 abnormal inflorescenses, but no galls. The two phenomena appear, 

 therefore, to be of separate origin, while the possible inheritability of 

 the abnonnality appears to be negatived. 



Experimental Cultures of Oenothera, by R. R. Gates. 



The seeds for all experiments were counted and then placed in 

 phials in water under a bell-jar and the air exhausted. In this way 

 much air was removed from the seed-coats, but this method was not 

 entirely satisfactory, since many of the seeds continued to float. 



