456 E. ELEANOR CAROTHERS 



A BCD aBCD abCD abcD abed 



AbCD AbcD abCd 



ABcD A Bed aBcd 



ABCd a B c D Abed 



a B C d 



A b C d 



To be specific if A = accessory, B the V-shaped dyad of 

 number 1 and C and D the indistinguishable ones of numbers 

 7 and 8, then, out of sixteen second spermatocytes, we should 

 have the accessory in eight-sixteenths, the accessory and V 

 of tetrad number 1 in four-sixteenths, any two V-shaped dyads 

 six-sixteenths, any three in four-sixteenths. As the one hun- 

 dred spermatocytes counted represent two hundred derivative 

 cells, we have: 



Expected Actual count 



A given V (Accessory or no. 1) § x 200 = 100 100 



Only one V | x 200 = 50 48 



Two given Vs (Accessor}' and no. 1 or those of 7 and 8) J x 200 = 50 46 and 47 



Any two V's f x 200 = 75 84 



Three given V's (nos. 1, 7, 8 or accessory, 7, 8) f x 200 = 25 22 and 21 



Any three V's | x 200 = 50 48 



All four V-shaped ." ^ x 200 = 12| 8 



Considering that these figures are based on onry one hundred 

 first spermatocytes, the results are probably as near the expec- 

 tations as could be anticipated for any objects on the basis of 

 chance distribution for a like number of trials. 



b. Recombination of the homologies of the J-shaped tetrads in 

 eighty-two individuals of T rimer otropis (?) fallax (?). The use of 

 the word recombination may require some explanation. The 

 two dissimilar homologues composing a heteromorphic tetrad are 

 segregated into different male gametes. For example the atelo- 

 mitic dyad of a J-shaped tetrad goes to one pole and the telo- 

 mitic dyad to the opposite pole. Gametes carrying each kind of 

 homologue would therefore be formed. If we may assume that 

 the form of the homologues remains constant and that a female 

 may carry J-shaped (heteromorphic) tetrads and produce dif- 

 ferent types of gametes, in respect to such chromosomes, like 

 those of the male; then, if free fertilization occurs, there should 

 be found in the offspring all possible recombinations of the 



