CHROMOSOMAL VARIATIONS AND THE FORMATION 

 OF THE FIRST SPERMATOCYTE CHROMOSOMES 

 IN THE EUROPEAN EARWIG, FORFICULA SP.^ 



FERNANDUS PAYNE 



SIXTY-FOUR FIGURES 



During the months of September and October, 1912, 1 collected 

 a nmnber of specimens of Forficula in the vicinity of Wiirzburg. 

 The species remain in doubt, but probably most of my speci- 

 mens are auricularia. From the chromosomal history, one 

 other species may be present in my material. The gonads were 

 fixed in Flemming and Bouin and the sections stained with Hai- 

 denhain's hemotoxylin. A superficial study of the slides indi- 

 cated that irregularities in chromosome distribution were present. 

 Nothing further was done, however, until my return to Bloom- 

 ington. Upon looking up the literature, I found that a number 

 of investigators had worked on Forficula auricularia, but their 

 results were not in agreement. 



As early as 1885 Carnoy described the number of chromosomes 

 in the spermatocyte divisions as varying from 10 to 14. Two 

 years later La Valette St. George ('87) described 12 in the first 

 and 12 to 14 in the second spermatocytes. Sinety ('01) found no 

 irregularities and gave the spermatogonia! number as 24 and the 

 spermatocyte 12. In two papers Zweiger ('06) works over the 

 field in detail and finds the spermatogonia! number 24 or 26 and 

 the spermatocyte 12, 13 or 14. The observations of Stevens 

 ('10) are more nearly in agreement with those of Sinety ('01). 

 She finds the spermatogonia! number 24, the first spermatocyte 

 12 and usually 12 in the second, although 11 and 13 chromosomes 

 are occasionally counted in this division. She also describes an 

 unequal pair of idiochromosomes. The explanations which these 

 authors offer are no more in agreement than their observations. 



' Contribution from the Zoological Laboratory of Indiana University, No. 134. 



559 



JOURNAL OF MORPHOLOGY, VOL. 2.j, NO. 4 

 DECEMBER, 1914 



