SPERMATOGENESIS OF SCUTIGERA FORCEPS. 157 



mosomes and regard in the same way the composition of the 

 nucleoles. 



Blackman ('oi, '03) on the other hand, confined his work on 

 Scolopendra heros principally to nuclear structures. According 

 to him the large nucleolus found during the resting stage is 

 almost entirely chromatic in nature, and from this body the chro- 

 mosomes are directly derived at the opening of the active pro- 

 phase. This structure, which he called the " karyosphere," 

 would correspond to Carney's nucleole nucleinien. 



TECHNIQUE. 



The animal from which my material was obtained is the black- 

 banded Centipede, or wall-sweep Scutigcra forceps. The spec- 

 imens were collected during the spring and early summer. The 

 animals were killed and their testes immediately removed and 

 placed in Gilson's aceto-nitric sublimate, where they were left for 

 a length of time ranging from twenty-four to forty-eight hours. 

 They were then removed, washed in running water for several 

 hours, run through ascending grades of alcohol from 30 per cent, 

 to 70 per cent., where they were treated with iodine solution to 

 remove the crystals of corrosive sublimate, and preserved in 

 fresh 70 per cent, alcohol. The material was embedded by the 

 usual method in paraffin ; sections varying in thickness from three 

 to six micra were cut, fixed to the slide with albumen water and 

 stained by one of the following methods : 



The staining method productive of the most satisfactory results 

 is Heidenhain's iron-hrematoxylin. Sections were stained for 

 observing different structures by varying the degree of extraction 

 of the color. For some purposes, however, the sections stained 

 with iron-haematoxylin and counter-stained with congo-red were 

 more satisfactory. For the purpose of a micro-chemical test, 

 Flemming's three-color method may be employed to great advan- 

 tage. When stained in this manner, the different parts of the cell 

 take on the following colors : the net-work stains a grayish pur- 

 ple, the centrosomes red, the chromatin in the dividing stages and 

 in the karyosphere stains a transparent red, and in the diffuse con- 

 dition found in the prophases and late telophase stains purple. 

 The achromatic nature of the neucleoli is shown by the fact that 



