GAMETfC COUPLING AND KEPULSION IN THE SILKWORM. 137 



VII. Historical Review. 



Since the phenomenon of gametic coupling was first adequately studied in 

 the Sweet Pea by Bateson and his collaborators in 1906, a number of similar 

 cases have been observed by these and many other authors. The experimental 

 results hitherto known in this field are summarized in the following pages. 



A List of the Known Cases of Gametic Coupling 

 and Repulsion. 



I. Gametic Coupling. 



A. Plants. 





**- _L YMr 



Sweet Pea 



A) 1 ' Blue factor^ and B) long pollen, 

 a) Red colour and b) round pollen. 



7:1:1:7 



Saunders, and 

 Punnett. 



1906 



Sweet Pea 



A) Blue factor and B) long pollen. 

 a) Red colour and b) round pollen. 



15 : 1 : 1 : 15 4) 





100s 



Sweet Pea 



A) Dark axil and B) fertility. 

 a) Light axil and b) sterility. 



15 : 1 : 1 : 15 





1908 



Pea (PisumJ 



A) Tendril and B) round seed. 

 (i) Xo-ttnidril or 'acacia' type and b) 

 wrinlded seed. 



63 : 1 : 1 : 63 





1911 









3) The 7 : 1 series was observed in the Fz families of the cross Blanche Burpee X 

 Bitty BoMbr-am, while in F$ of the same cross the gametic system followed was of 15 : 

 1 : 1 : 15 type. The latter was also the case with the F- offspring of Bw>h X Cupid crosses. 



