Chromosomal Variations in Earwigs 225 



CHROMOSOMAL VARIATIONS IN THE EARWIG, 

 ANISOLABIS ANNULEIPES LUCAS. 



W. p. Morgan, Indiana Central College. 



The specimens for the following study were collected in the locality 

 of New Orleans, La. and Mississippi College, Miss. The study, how- 

 ever, was based largely on the Louisiana material. The specimens were 

 identified as Ayiisolabis annuleipes Lucas by A. N. Caudell, Bureau of 

 Entomology, Washington D. C. The gonads were fixed in Flemming 

 and the sections were stained with Haidenhain's hematoxylin and a few 

 were counter-stained with eosin. All the work was done under the 

 direction of Dr. Fernandus Payne to whom the writer is greatly indebted 

 for helpful criticism and advice. 



Several workers beginning with Carnoy in 1885 have described 

 the spermatogenesis of the European earwig and there has been much 

 disagreement in the descriptions and explanations of the various authors. 

 Payne^ reworking the spermatogenesis proves beyond a doubt that many 

 irregularities do exist in this species and in this way accounts for some 



■# ^ m 



1 2 3 



Fis. 1-1. Spermatojionial metaphase shovvin.n' lio chromosomt'S. 



of the disagreement of the preceding workers. Although the following 

 study does not have a direct bearing on these explanations, neverthe- 

 less it does definitely show certain irregularities and probably with a 

 more extended study of several species of earwigs we may find that 

 most of the chromosomal irregularities of this whole group of insects 

 will become understandable. The writer is at present working on a 

 comparative study of the spei matogenesis of the earwigs. 



Description. The speimatogonial number in Anisolabis anmdeipes 

 Lucas is 25 (figs. 1, 2, 3, 4). This was shown to be the case by a 

 great many counts of clear metaphase plates. 



During the growth period one or more dark staining bodies are 

 seen in the nucleus (figs. 5, 6, 7). By following these bodies during 

 this period and the early prophases it was found that one body very 

 definitely continues as a bivalent chromosome. As shown in figures 8 

 and 9 the parts of the bivalent are not of equal size. The dark 

 staining body and its changes in the growth period and early prophase 

 is similar to that described by Payne in the European earwig except 

 that he did not find the body bilobed. In the latter part of the pro- 

 phase this unequal pair of chromosomes, which the body very definitely 



^ Payne, Feinandus. Chiomosomal Variations and the Formation of the First 

 Spermatocyte Chromosomes in the European Earvvis', Forficula sji. -Journal of 

 Morphology, Vol. 25, No. 4. 



"Proc. oSth Meeting, 10l!2 (1923)." 

 15—23870 



