ON THE SPERMATOGENESIS OF THE EARWIG ANI- 

 SOLABIS MARITIMA.i 



HARRIET RANDOLPH. 



The material for the examination of the germ cells of Anisola- 

 bis maritima came from a colony of these earwigs at Bryn Mawr. 

 On account of the interest in the behavior of the chromosomes 

 in the germ cells of insects, it seems desirable to add this group 

 to the list of those that have been investigated recently in this 

 country. 



The material was preserved in Flemming's stronger fluid or in 

 Gilson's mercuro-nitric solution and stained by Heidenhain'siron- 

 haematoxylin method or with thionin. 



A preliminary paper on the spermatogenesis of Forficula aiiriai- 

 laria by Zweiger, '06, which appeared in 1906, contains refer- 

 ences to the bibliography of the subject. 



In the youngest stages found at Bryn Mawr each cyst con- 

 tained several spermatogonia. In these cells (Fig. i)in the rest- 

 ing stage there is a large spherical body which stains like chro- 

 matin. 



In the equatorial plate of the dividing spermatogonia seen in 

 polar view there are twenty-four chromosomes and a plasmosome 

 which stains faintly (Fig. 2). 



In the telophase of the last spermatogonial division two chro- 

 mosome rods become connected with the plasmosome and 

 remain condensed throughout the growth stages of the first sper- 

 matocytes. 



Synizesis and synapsis stages are shown in Figs. 3 and 4, and 

 the spireme in Fig. 5. At some time during the growth stages 

 of the spermatocyte the heterochromosome pair separate from 

 the plasmosome, forming a single rounded mass which lies free 

 in the nuclear space (Figs. 6 and 7). 



The splitting of the chromosomes is shown in Fig. 8. In Fig. 

 9 chromosomes from the prophase of the first spermatocyte are 



1 For the identification of the species I am indebted to the kindness of Mr. J. A. 

 G. Rehn, of the Academy of Natural Sciences, Philadelphia, Penna. 



Ill 



