362 SIDNEY J. HIOKSON. 



(Stage F), showing the fusion of the germ nuclei (G. m.). On the left the two 

 nuclei have not completely joined ; the chromatin is in the form of a coarse 

 skein with thickened nodes. Oa the riglit the pair have fused, and the 

 chromatin has assumed an irregular asterid form. No. 140. 



13. Section through the conjugative processes after the fusion of the germ 

 nuclei to form tlie segmentation nuclei (S. m.). The segmentation nuclei 

 become mitotic soon after their formation, but the axes of the figures are not 

 parallel with the membrane nor with one another. In this case the upper figure 

 is seen in longitudinal section and the lower in transverse section. No. 117. 



14. Section through a Dendrocometes at an early stage in the forma- 

 tion of a gemmula to show the normal mode of division of the meganucleus. 

 B. B. Bands of concentric modified cytoplasm which form the peritrichous 

 bands of cilia of the gemmula. No. 34 s. 



15. Section through one of a pair of- conjugates in Stage K, showing the 

 fragments of the old meganucleus and the new meganucleus. m., One of the 

 micronuclei ? No. 92. 



16 — 18. Three stages in the division of the micronuclei. 16. Imme- 

 diately after the division of the chromosomes. 17. The chromosomes separated 

 to the poles of the figure. 18. The chromosomes collected into a granule of 

 chromatin at each of the poles, and the achromatin in the form of an elongated 

 spindle. 16 and 17, No. 129. J 8, composition drawing from several prepara- 

 tions. 



19. Section through a Dendrocometes at the close of conjugation. It 

 shows the rare condition of two new meganuclei. The old meganucleus has 

 almost completely disintegrated. No. 74 E. 



Note. — In Stage K, when the old meganucleus has fragmented, it is 

 extremely difficult to distinguish the micronuclei from fragments of the old 

 meganucleus. I have therefore made no attenijjt to reconstruct Fig. 15 and 

 Eig. 19, so as to show all the micronuclei in their correct relative positions. 

 These two figures were drawn with the assistance of the camera lucida from 

 one section only of each series of sections. 



