CYTOLOGY OF ANISOLABIS MARITIMA BON. 235 



of 1915, suffered many delays due to the World War, but was 

 taken up again in the spring of 1920. 



I wish to express my thanks to the American Association for 

 the Advancement of Science, which, through its Commitiee on 

 Grants for Research, has enabled me to purchase microscopical 

 lenses suitable for cytological study. These lenses have aided 

 greatly in the completion of the paper. 



2. HISTORICAL REVIEW 



Two of the Forficulidae have been previously worked upon 

 from a cytological standpoint, Forficula auricularia and the pres- 

 ent species, Anisolabis maritima; the bulk of the work having 

 been done upon the former species. The accounts claim a great 

 variability -in the diploid and haploid number of chromosomes, 

 and several combinations of sex-chromosomes have been 

 described. 



The most recent and detailed contribution to the cytology 

 of the forficulids is that of Payne ('14) on the variability of the 

 chromosomes of Forficula. Payne states that the spermato- 

 gonial metaphases show from 24 to 27 chromosomes, twenty- 

 four being the most usual number. The spermatocytes were 

 found to have from 11 to 14 chromatic elements present. Zwei- 

 ger ('06) states that the spermatogonial count was 24 or 26, 

 the latter number being the more prevalent. He states that 

 either 12 or 13 chromosomes may appear in the primary spermato- 

 cytes, and 12 to 14 in the secondary spermatocyte metaphase 

 plates. 



Stevens ('10) considered 24 the correct spermatogonial number 

 and 12 the haploid number, one of the twelve seen in the primary 

 spermatocytes being an unequal hetero chromosome group, which 

 separated reductionally in the first maturation division. 



Pantel ('12), whose work deals mainly with the degeneration 

 of cells due to the presence of protozoan or insect parasites, 

 described a variable number of chromosomes in Forficula. Sper- 

 matogonia have either 25 or 26 chromosomes; and spermato- 

 cytes, 11 to 13 chromosomes. He does not insist, however, that 



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