ON PHYSIOLOGICAL CHROMOMERES. 



621 



and oblonga in my cultures of lata and scintillans. The lata plants 

 had been fertilized by means of the pollen of 0. Lamarckiana, 

 while for scintillans selffertilization has been the rule. In the following 

 tables the amount of the cultures is given with the percentage 

 figures for the different derivates. 



A. Percentage of oblonga from scintillans. 



Together 7380 



10.5 



18 



70 



1.5 



B. Percentage of albicla from lata. 



Together 1802 



9 



19 



69 



The mutants of the first table were 12 lata, 6 albida, 1 pallescens, 

 1 cana and 1 nanella and some dubious forms. Those of the second 

 table were 25 oblonga, 1 scintillans, 3 pallescens, 1 semigigas, 8 nanella 

 and some others. 



From these tables we may conclude that the splitting off is a 

 regular phenomenon, that it amounts in average to about 10%, 

 and varies around this figure in the ordinary way, especially in the 

 smaller cultures. There must therefore be a high degree of linkage 

 in each of the two cases and this shows that the complex factors 

 for each pair must be included in the same chromosome. 



Gates has recently shown that lata appears as the basal form in 

 the series of typical mutants, a fact which is wholly in accordance 



