DEPARTMENT OF BOTANICAL RESEARCH. 81 



cultures which have been introduced at Tucson are in their fourth, 

 tenth, twelfth, and eighteenth generations, and all show the same 

 uniform progressive change in their water-retaining capacity during 

 hibernation. In no instance has it been possible to reverse this change 

 by returning the stocks from Tucson to Chicago. Accompanying this 

 change are behavior changes, especially to desiccation, and in rates of 

 reaction to stimuli changes not observed in their early stages and only 

 seen after considerable alteration had taken place. In that there is a 

 wide range in any culture of these behavior changes it seems probable 

 that the alteration is a gradual one, but this must be checked by close 

 observation of future introductions. 



Morphological changes in pattern, color, and size continue as noted 

 in previous reports, and most notable are the reductions of portions of 

 the elytral pattern and of the ventral surface. These changes are 

 genetic, as shown by test crossings with the basic stocks, and behave as 

 Mendelian recessives and have not regressed to the original condition 

 by living at Chicago for two to four generations. 



These alterations are of the order observ^ed in ecological varieties 

 in nature or in varietal states under domestication. The genetic 

 behavior is also the same, due to "losses," thus giving "recessives" in 

 crosses with the nonnal. This, while true of the morphological changes, 

 is the opposite in the observed physiological alterations, i. e., water- 

 relation, altered behavior, which are "dominants." 



MUTATING STEM STOCKS. 



Two chief series of these are now carried at Tucson — one C. H. 156.8, 

 a synthetic product of three species, L. dece7nlmeata , oblongata, multi- 

 tceniata; the other, C. H. 15.7, a compound of L. decemlineata and 

 multitceniata. The manner of production has been recorded in pre- 

 ceding reports. 



In the past year the stem stocks which were not subjected to experi- 

 ment continued to breed tine with httle variabilit}^ In the C. II. 

 156.8 series only slight mutations have been produced thus far, and 

 they are aU in the elytral pattern and are of an order unknown in the 

 parent species. 



The mutating lines of the C. H. 15.7 series continued their behavior 

 in this respect during the year. The mutants in this series are of two 

 types: (1) recombinations of characters from the original parents, and 

 (2) alterations of these. Of the first no new types were discovered 

 during the year and apparently the possible array has been exhibited. 

 More than 20 of these recombination types have been observed and 

 are being tested out in the laboratory at Chicago. Two or three years 

 more will be requhed for completion. 



One interesting fact was demonstrated in the year, namely, that some 

 of the mutants mutated, either regressively, towards the stem stock. 



