BATESON AND PUNNETT 



6), we obtained a much more definite 

 result. From it eight families, hetero- 

 zygous in colour and pollen, were 

 raised (Table II, Nos. 20-27). On 



59 



adding together the results of these 

 nine families, we obtain the following 

 numbers: 



It is obvious that the numbers in this 

 group of families accord very closely 

 with the figures expected on a 15 : 1 : 

 1 : 15 basis; and the view that this is 

 the system actually followed receives 



confirmation from the distribution of 

 the pollen and colour characters in the 

 Fo families from the Bush ^ X Cupid 

 crosses (Table I, p. 7), where the fol- 

 lowing figures were obtained: 



From the closeness with which the 

 recorded results agree with expecta- 

 tion, it is evident that here again we 

 are concerned with a 15 : 1 : 1 : 15 

 series. And when we come to deal with 

 the inheritance of sterility in the Sweet 

 Pea (p. 16), we shall meet with an- 

 other case, in which we are undoubt- 

 edly concerned with a similar gametic 

 series. We may take it, therefore, that 

 there is good evidence for the existence 

 of gametic coupling in the 15:1:1: 

 15 series, as well as for the derivation 

 of the families exhibiting the higher 

 form from families in which the lower 

 occurs. We have, then to recognize 

 that in some families the coupling fol- 

 lows one system and in others another. 

 Each process is, nevertheless, definite. 

 As yet, however, we have not per- 

 ceived any circumstance to which the 

 distinction can be attributed. 



In an earlier paragraph, we men- 

 tioned that, owing to the partial cou- 



pling of long pollen with purple, we 

 should expect hooded purples and 

 hooded whites to be found very rarely 

 with round pollen. When the gametes 

 are produced in series of 16, i.e., 1 

 purple long, 1 purple round, 1 red 

 long, and 7 red round, it is clear that 

 the chances of two purple round 

 gametes meeting are only 1 in 16-, i.e., 

 in 256 in families where reds occur. Of 

 these 256 plants, 64 are homozygous 

 for purple. Consequently, the chances 

 of a homozygous purple having round 

 pollen are 1 in 64. In families where 

 hoods occur all the homozygous pur- 

 ples are hooded, and we should, there- 

 fore, look for one round hooded pur- 

 ple in 64. In the four Fi families (Nos. 

 1-4), 1 round hooded purple occurred 

 among 83 plants. Again, since the 



•"5 The flower of the Bush plants used was a 

 hooded white, exactly like that of Blanche 

 Burpee. 



