MATERNAL INHERITANCE 233 



early loss of the paternal chromosomes may account for 

 some of the cases of maternal embryos, there may also 

 be cases where the chromatin may divide normally but 

 fail to produce any conspicuous effects on the cytoplasm 

 sufficiently soon to become apparent in the young fish. 

 In this connection the tobacco crosses described by 

 Groodspeed and Clausen may be recalled. In these cases 

 it was a particular group of chromosomes, regardless of 

 whether it was of paternal or of maternal origin, whose 

 '^reaction system'' dominated in the F^ hybrid. 



