THE SPERMATOGENESIS OF THE MYRIAPODS. 



189 



other stage of mitosis. In the early telophase where the two new 

 cells are almost completely constricted the chromatin is arranged 

 in a densely packed mass of chromosomes in which the individual 

 elements are indistinguishable. Later (Fig. 3) these elements 



FIG. I. X I >44 dia. Spermatogonium of Scolopendra heros in the condition of 

 rest. All of the chromatin is aggregated into one mass, the karyosphere. 



FIG. 2. X I j44 dia. Spermatogonium in prophase. The chromatin is all with- 

 drawn from the karyosphere and is now in the form of 33 small chromosomes all of 

 which, with the exception of the accessory chromosome, are of a granular consistency. 

 This element is homogeneous. The centrosomes are to be seen in the cytoplasm 

 near the nucleus. 



FIG. 3. X I i44 dia. Telophase of the last Spermatogonium. Synapsis. Cyto- 

 plasmic division nearly complete. All chromosomes with exception of accessory, be- 

 coming granular. No nuclear membrane. Centrosomes at poles of the cell. 



FIG. 4. X I >44dia. Later telophase. Synapsis. Chromosomes have lengthened 

 still more. Accessory chromosome still intact. Growth of the cell has begun. 



FIG. 5. X I >44 dia. Early spermatocyte. Nuclear membrane beginning to 

 form. Accessory has taken up a peripheral position. Mass of chromatin has loosened 

 considerably and is now seen to consist of segments equal in number to one half the 

 spermatogonial elements, minus the accessory chromosome. Centrosomes have mi- 

 grated from their polar position. 



begin to lose their homogeneous consistency and to lengthen 

 out into densely granular segments. Owing to the dense mass- 

 ing of the chromosomes during this and following stages, the ex- 



