600 RECORD OF MEETINGS OF THE 



The minutes of the last meeting of the Section were read and 

 approved. 



The following program was then offered : 



E. B. Wilson, Observations on the Chromosomes in 



Hemiptera. 

 H. E. Crampton, Correlation and Selection. 



Summary of Papers. 



Professor Wilson's paper presented the results of an examina- 

 tion of the mode of distribution of the chromosomes to the 

 spermatozoa in Lygcsus turcicus, Ccenus delius, Podisus spinosus 

 and two species of Euchistus. In none of these forms is an 

 accessory chromosome (in the ordinary sense) present, all of the 

 spermatozoa receiving the same number of chromosomes, which 

 is one half the spermatogonial number (the latter number is 

 in Podisus sixteen, in the other forms fourteen). In all these 

 forms, however, an asymmetry of distribution occurs such that 

 two classes of spermatozoa are formed in equal numbers, both 

 receiving a ring of six chromosomes (in Podisus seven) that 

 are duplicated in all the spermatozoa, and in addition a central 

 one which in one half the spermatozoa is much smaller than 

 in the other half. These corresponding but unequal chromo- 

 somes (which evidently correspond to some of the forms described 

 by Montgomery as "chromatin nucleoli" and agree in mode of 

 distribution with that which this author has described in the 

 case of Euchistus tristigmus) may be called the "idiochromo- 

 somes." They always remain separate in the first division, 

 which accordingly shows one more than one half the sper- 

 matogonial number of chromosomes, but at the close of this 

 division conjugate to form an asymmetrical dyad, the number 

 of separate chromatin- elements being thus reduced from eight 

 to seven (in Podisus from nine to eight). A reduction of the 

 number to seven in the first division, such as has been described 

 by Montgomery as an occasional or usual process in Euchistus 

 and Ccenus, was never observed. In the second division the 

 asymmetrical idiochromosome-dyad separates into its unequal 

 constituents, while the other dyads divide symmetrically. 



