I. A FURTHER STUDY OF THE CHROMOSOMES OF 

 THE REDUVIIDAE. 11. THE NUCLEOLUS IN THE 

 YOUNG OOCYTES AND ORIGIN OF THE OVA IN 

 GELASTOCORIS 



FERNANDUS PAYNE 



From the Zoological Laboratory of Indiana University^ 



TEN FIGURES 



I. A FURTHER STUDY OF THE CHROMOSOMES OF THE REDUVIIDAE 



Since describing several irregularities of chromosome distribu- 

 tion in this family ('09 and '10), I have been seeking further 

 information in regard to the origin of such irregularities. I 

 expressed the view ('09) that these irregularities probably arose 

 by the large idiochromosome breaking up into two, three, four, or 

 five elements. While I had no authority for believing it, I looked 

 upon these changes as recent ones, and hoped to find a species in 

 which such a change was taking place. During the past summer, 

 I made a collecting trip through the West and South. A study 

 of this material has thrown some doubt on this view. I have 

 five species of Sinea (diadema, rileyi, confusa, complexa, spinipes) 

 and they are distributed from Massachusetts to California. 

 Four of them (spinipes, confusa, complexa, and diadema) show 

 the same number and size relations of the chromosomes and the 

 same type of distribution as Sinea diadema (Payne, '09). From 

 this fact it would seem that both the number of chromosomes 

 and the type of distribution existed before the genus split up into 

 these four species and before it became distributed over such a 

 wide area. Otherwise it is rather difficult to explain this con- 

 stancy in number and behavior of the chromosomes in the four 

 species. On the other hand a study of the chromosomes of Sinea 



1 Contribution No. 124. 



331 



JOURNAL OF MORPHOLOGY, VOL. 23, NO. 2 



