No. 450.] 



STUDIES ON THE PLANT CELL. 



447 



spindle where the nuclear plate formerly lay. Such thickenings 

 are granular accumulations formed by the contraction of the 

 central spindle fibers and mark the beginnings of the cell plate 

 (Fig. 8 d) that afterwards gives rise to the cell wall. When 

 the daughter chromosomes reach the poles of the spindle they 

 generally lie in a region of granular kinoplasm which results in 

 part from the contraction of spindle fibers and in some cases 

 from the breaking down of organized centrospheres {e. g., Coral- 

 Una, Pellia, Fucus, etc.). The daughter nucleus at this time 



Fig. 7. — Telophase of Mitosis, spore mother-cell oi Passijlora cterulea. «, very late anaphase ; 

 the daughter chromosomes are collected at the poles of the spindle, b, the commence- 

 ment of telophase ; the chromosomes have fused together and the daughter nucleus is 

 represented by an irregularly shaped mass of chromatin, c, the presence of small lacunae 

 within the mass of chromatin indicates the accumulation of nuclear sap in vacuoles, d, an 

 increased amount of nuclear sap, still held however within the mass of chromatin, and 

 consequent enlargement of the vacuole destined to become the nuclear cavity, tf, the 

 chromatin lias begun to break up into small masses so that it no longer holds the nuclear 

 sap which has established contact with the cytoplasm and is forming the nuclear plasma 

 membrane, y, nuclear sap in contact on all sides with the cytoplasm and a complete 

 nuclear membrane clearly established ; chromatin is very much broken up and two nucleoli 

 (n) have been formed, g, the resting nucleus with chromatin distributed in small masses 

 connected by a network of linin threads; a nucleolus fn) is shown ; the zone outside the 

 nuclear membrane is kinoplasm and its appearance indicates the approach of the second 

 mitosis in the pollen mother-cell. All figures after Lawson. 



(Fig. 7 a, b) is in its simplest terms, as explained in Section I, 

 a group of chromosomes surrounded by granular kinoplasm and 

 without the nucleolus, linin network or the vacuole which later 

 contains the nuclear sap. 



Telophase. — Telophase is the closing period of mitosis and 

 completes the organization of the daughter nuclei (see Fig. 7). 



