230 KATHARINE FOOT AND E. C. STROBELL. 



APPENDIX. 



We have just received Wilson's latest " Study on Chromo- 

 somes," No. V., 1 in which (in a footnote on page 159) he at- 

 tempts to explain what he calls our "entirely mistaken conclu- 

 sions " regarding the division of the accessory chromosome in 

 Anasa tristis as follows : 



"The regrouping of the chromosomes in the second division, 

 first described by Paulmier ('99) in Anasa tristis, is characteristic 

 of the Coreidae generally, an eccentric position of the idiochromo- 

 some being a nearly constant feature of the first division but not 

 of the second. Failure to recognize this fact in the case of Anasa 

 tristis seems to have been one of the main sources of error in the 

 entirely mistaken conclusions of Foot and Strobell ('07^, '07$) 

 regarding this species. (Cf. Lefevre and McGill, '08.) Demon- 

 strative evidence on this point is given by polar views of rather 

 late anaphases, in which every chromosome of each daughter 

 plate may be seen, in the same section. Such views, of which I 

 have studied many, both in Anasa and other genera, show that 

 one of the chromosomes may indeed occupy an eccentric position, 

 and may there divide ; but in such cases the odd chromosome is 

 always found elsewhere in the group, lying either in or near one 

 of the daughter groups and not in the other. When the odd 

 chromosome is eccentric it is found in one of the daughter groups 

 but not in the other." 



In order to speak with authority on the regrouping of the 

 chromosomes, some accuracy at least is expected in the identifi- 

 cation of the individual chromosomes. Paulmier's authority can 

 be dismissed when we recall Wilson's interesting discovery that 

 in Anasa tristis Paulmier erroneously identified the micro- 

 chromosome as the accessory (undivided) chromosome of the 

 second spindle. 



In Plate III. of our " Study of Chromosomes in the Spermato- 

 genesis of Anasa tristis" ('07) we show in Photos 27, 28, 33, 35, 

 36, 37, 38, 39, 42, 43, 44 and .45, late anaphases or early telo- 

 phases of second spindles demonstrating the ring-like formation 

 of the chromosomes, with one of the chromosomes eccentrically 

 placed or lagging. In our smear preparations this grouping is 



Jour. Exp. Zool., Vol. VI., No. 2, 1909. 



