WATER RELATIONS IN HIBERNATION. 245 



either view with any certainty, and accurate determination of 

 either of these is difficult, if not quite impossible. Regardless 

 of what the actual change may consist of, it is an evolutionary 

 modification, that is directly adaptive in response to altered 

 conditions of life, and as such is well worth careful examination 

 and further investigation. 



Perchance it may seem that it is easy to arrive at results of 

 this kind. To prevent any such misapprehension, the experiences 

 in the introduction of other species into the same environic 

 complexes may be cited. During the years in which these 

 experiments with L. decem-lineata have been in progress, there 

 have been introduced with the same care and persistency L. 

 signaticollis, diversa, undecimlineata, panamensis, multitceniata, 

 oblongata, haldemani, juncta, and dilecta, representing a diversity 

 of environmental origins and adjustments to temperature and 

 moisture during the hibernation period, and in none of them has 

 anything like the result described in decem-lineata been found. 

 The closest approximations thereto are in the species multit&niata , 

 oblongata, and signaticollis, all of which live in haibtats having 

 rather high rates of desiccation during the resting season, and 

 survival in the case of these introductions has been irregular, 

 and the product of favorable conditions in the particular winter, 

 rather than any alteration resulting from the introduction. All 

 of these species, further, live in areas in which the temperature 

 in the resting season is fairly high, so that there is no necessity 

 for the reduction of the water content to prevent elimination 



by frost action. 



INHERITANCE. 



It was shown in connection with some of the earlier tests 

 that the alteration when crossed with the normal condition 

 at Chicago, gave an FI that was completely eliminated during 

 the test of survival of the winter, and that F 2 showed a result 

 suggesting the survival of the recessive extractives of the normal 

 type. Further crossings of these have confirmed this original 

 finding and extended the information as to the behavior of the 

 alteration in inheritance, thus showing that the change between 

 the conditions of the populations at Chicago and Tucson is of a 

 gametic nature, and not somatic or temporary. 



