74 



Scientific Proceedings (48). 



conditions) to transmit the abnormal abdomen. This is best 

 demonstrated by linking the factor for abnormal abdomen A with 

 another sex-linked factor, such as the b factor in the yellow 

 mutant, or the c factor in the white mutant, or to both together 

 as in the two examples given below. 



GWN9 / GWN& 



' GRA 9 



05 



56 



X 



0 



GRN9 



0 



4 



32 



GWN9 



88 



49 



34 



GWNJ* 



98 



49 



19 



YRAc? 



81 



47 



7 



. YRNtf 



1 



2 



25 



■ GWA<? 



50 



21 



9 



GWN& 



1 



24 



24 



GRA 9 



76 



3 



0 



GRN9 



5 



49 



60 



YRN9 



45 



93 



61 



. YRNtf* 



49 



29 



30 



YRN9 \GRN9 

 GWA o* / YRNd* 



The tables show that in the expected classes for abnormal 

 abdomen A this character at first appears but later is replaced by 

 the normal character N. When the normal flies (of the last sort) 

 were tested they were found to transmit abnormality. The other 

 classes that are genotypically normal remain so in the next 

 generation. Cultures that had produced only abnormal flies for 

 nine generations under wet conditions were allowed to dry out 

 when all the later-hatched flies became normal. These were then 

 placed under moist conditions, and all of their offspring were as 

 abnormal as their ancestors had been. 



54 (663) 



Sources of error in serological work. 

 By WILFRED H. MANWARING. 



[From the Rockefeller Institute for Medical Research.] 



I have been engaged for some time in attempts to determine 

 the approximate chemical nature of certain bactericidal substances 

 obtained from horse leucocytes. My earlier attempts to isolate 

 and identify these substances were characterized by inconstant 

 and inconsistent results. This led to an examination of the 



