560 JOHNSON. 



EXPLANATION OF PLATE XXV. 



Regeneration of frontal field and nuclear changes of S. ctericleus. 



Fig. 38. Specimen in process of regeneration of mouth and frontal field. The 

 buccal portion of adoral zone has already atrophied, and the buccal pouch is much 

 reduced; the meganucleus (mgn.) has elongated after condensation. Zeiss, y^. 



Fig. 39, A and B. Two successive regenerations of same individual. From 

 life; 39 B one-and-a-half hour later than 39 A. |. 



Fig. 40. Distal individual just after a fission which, in its earlier stagfes, pro- 

 ceeded like a regeneration. Disorganization of stripes in ramifying zone, due to 

 abnormal mode of fission. From life. Zeiss, if. 



Fig. 41 a-i. Series showing changes in living meganucleus from time of great- 

 est condensation to beginning of nodulation. Period of observation, 1.17 p. M. to 

 2.20 p. M. Zeiss, ^f X ca. 160. 



Figs. 42, 43. Two consecutive stages in division of meganucleus, after comple- 

 tion of nodulation. In Fig. 43 division has just taken place. From preparations. 



Zeiss, — {cam.) = X i 50. 



Figs. 44, 45. Two modes of nodulation of meganucleus; 44 somewhat earlier 



than 45. Zeiss, - (cam.) = X 380. 



Fig. 46 «-^. Series showing changes in living meganucleus from division (in 

 condensed stage) to complete nodulation. Zeiss, -^^ = ca. X 100. 



Fig. 47 a-/i. Changes in living meganucleus from beginning of condensation to 

 beginning of renodulation. Zeiss, -fj; = ca. X 100. 



Fig. 48. Tangential section of meganucleus in condensed state, with si.\ 

 micronuclei, two of them in mitotic division. Corr. sublimate, picro-carmine. 

 Zeiss, homog. immers. 2 mm. and comp. oc. 4 = X S57. 



