196 



BOTANICAL GAZETTE 



[march 



Fig. 57. — Oogonium in which two nuclei show early metaphase: two figures 



perpendicular to each other. 



Fig. 57a.— One of two figures in fig. 57, under higher magnification. 



Figs. 58a, 58ft, 58c. — Three sections of the same nucleus in early metaphase: 

 the middle one shows 32 univalent chromosomes in the equatorial plate. 



Fig. 59. — Oogonium with two nuclei in early anaphase. 



Fig. 59a. — Nucleus from fig. 59, under higher magnification: nucleolus still 

 remains; two centrosomes still showing conspicuous radiations. 



Fig. 60. — Oogonium with two nuclei in late anaphase. 



Fig. 60a. — Nucleus from fig. 60, under higher magnification. 



Fig. 61.— Telophase: two centrosomes with their radiations still recognizable; 

 central spindle about to disappear. 



Fig. 62.— Late telophase: chromosomes aggregated at poles beginning to 

 vacuolize; meshes of cytoplasm arranged somewhat radially from two pok 

 toward the equator. 



Fig. 63.— Section of oogonium cut transversely through its axis, after late 

 telophase of second mitosis : only three of four daughter nuclei are figured; between 

 every two of these three nuclei is an irregular fibrillar arrangement of cytoplasm. 



Fig. 64.— Late prophase of the third division, viewed from pole: chromosomes 

 (32) in the equatorial plate before splitting. 



Fig. 65.— Metaphase: nuclear membrane still present; most of the chromo- 

 somes arranged in the equator show their ends, the stage being just after splitting. 



Fig. 66.— Late metaphase: nuclear membrane almost dissolved; daughter 

 chromosomes beginning to separate. 



Fig. 67— Anaphase: nuclear membrane has disappeared, the contour 

 the spindle-shaped nucleus undisturbed. 



PLATE XI 



t 



rcrmtzanon ana segmentation oj jermizeu cg& 

 Figs. 68a, 68b.— Two sections of the same nucleus in resting condition, from 



a discharged egg before fertilization, showing delicate ragged chromatin too 



two nucleoli; a single centrosome close to the nuclear membrane, without any 



radiations (fig. 68b). 



Figs. 69a, 696.— Two sections of the same nucleus of an egg when a spen» 



nucleus has just coalesced with it; fig. 69b shows a new centrosome whic ^ 



appeared at the point of the nuclear membrane where the sperm entered; 



other centrosome, of earlier appearance, shown in fig. 69a, seems split into two . 



this time; numerous granules surrounding the nuclear membrane stain eep.^ 

 Figs. 70a, 700.— Two sections of the same nucleus of an egg after coal< f 

 1 sperm nucleus, a little later staw than £0 fin The sperm nucleus has ^ g 



sperm nucleus, a little later stage than fig 



-r-»-» u ^'tus, a. mue later stage man jig. 09. me sjjc"» — — .^ n g 



to disintegrate, a delicate chromatin reticulum of the egg nucleus still rem 

 in the resting condition. %inte . 



Figs. 71a, yib, 71c— Three sections of the same fusion nucleus: the J^ 

 grating sperm nucleus has comoletelv minded with the contents of egg nu 





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