102 ANNALS NEW YORE ACADEMY OF SCIENCES 



bility of the ticking expressing itself may be realized, so that the "gray 

 without yellow" may in reality be a ticked hair, as first suggested. 



Although I have made no measurements or weighing, it appears that 

 the hybrids between the waltzer and common mice are larger than the 

 waltzer and possibly not as large as our common domesticated races. In 

 the second generation, I have obtained both large individuals and small 

 mice, as well as intermediates, the first as large as our common form, the 

 latter as small as the waltzer. It appears that the size character also 

 segregates, at least to some extent. 



Yerkes has pointed out that the older waltzers are deaf. In order to 

 study the inheritance of deafness, I tested many of my domesticated races 

 of mice and found that in them also there is a large percentage of animals 

 that seem to be entirely deaf. It becomes evident, therefore, that the 

 problem would be complex, unless races were first produced like the 

 waltzers that are uniformly deaf, but as I had no such races and did not 

 succeed in crossing wild mice and waltzers, it does not appear worth while 

 to give here the result of my observations on my hybrid mice. I hope to 

 continue this experiment later. 



Artificial Waltzers 



The curious effect of acetyl-atoxyl on mice has been described by Ehrlich. 

 It causes them to run about in circles in much the same way as do the 

 true Japanese waltzing mice. This coincidence in behavior led me to test 

 whether mice that have been made to waltz by artificial means would 

 transmit their acquired character. 



The injections were made for me by Dr. B. T. Terry, of the Eockefeller 

 Institute for Medical Eesearch, and I am greatly indebted to him for the 

 time and skill expended in producing these waltzers. In some cases, one 

 injection sufficed to bring on in a few days the circus movements; in 

 others, two or three doses were necessary, and some mice failed entirely to 

 become waltzers. In one case, the mouse was pregnant and the injection 

 caused abortion of two of her young, but the rest of the litter developed 

 to full term. None of these waltzed later. 



I have made a number of pairings between the artificial waltzers and 

 normal mice. None of the offspring waltzed, but since the waltzing of 

 waltzing mice is recessive, this might be expected to occur even if the 

 habit is inherited. Therefore I inbred these I\ mice, but obtained only 

 normal mice. In two or three cases, I have had young from a pair that 

 were both waltzers. None of these or their progeny waltzed. I conclude, 

 therefore, that so far as the evidence goes, the acquired character is not 

 transmitted. Although the results were negative, nevertheless the evi- 



