September, 1922.] SINOTO—I.RIS JAPONICA. 105 



figures are clearly observed, but not so in the latter. In the greater 

 part of preparations the whole appearance of the pollen mother-cells 

 found in the sections of the loculi suggests the probability that the 

 cytoplasm and other ingredients of the pollen mother-cells have been 

 damaged by some external injuries. 



With regard to the fate of the extruded materials the descrip- 

 tions by Digby (1) and Gates (8) are at some length. They observe 

 various features of the extruded bodies according to the stages of 

 nuclear division, and they seem to explain these features as a 

 continuous process. In Iris japonica various changes in the extruded 

 portions are also to be seen, but I rather think that those changes 

 should not be interpreted as a continuous process. This will be 

 stated later. 



Embryosac mother-cells : — The brief description that Digby (l) 

 has given with regard to Galtonia candicans appears to be the only 

 instance, so far as I know, of this phenomenon in the embryosac 

 mother-cells. In Iris japonica fragments of chromatin or small buds 

 thrown off from the nucleolus are often found in the nuclear cavity, 

 although the extrusion of the nuclear substance from the embryosac 

 mother-cell into the cytoplasm of the adjoining nucellar cells fails to 

 be observed. A large cell represented in the centre of Fig. 14 is an 

 embryosac mother-cell whose nucleus is in the condition of synizesis, 

 the synizetic ball with a nucleolus being apparently pressed against 

 one side of the cell membrane. 



Somatic cells :— The extrusion phenomena of the nuclear substance 

 in the somatic cells as due to the action of temperature or injury by 

 cutting or stripping were reported by several authors (9, 10, 11, 15, 20). 

 However in the tapetal-, integumental-, nucellar cells and the wall 

 cells of ovary of Iris japonica which were not acted upon by high or 

 low temperature nor injured by the section knife etc. the extrusions 

 are not infrequently observed. Fig. 13 indicates a case in the wall 

 cell of the ovary. 



Tapetal cells : — The tapetal cells in Iris japonica include generally 

 two nuclei at the time of the synizesis stage of pollen mother-cells. 

 The extrusion in the tapetum is observed during the stages from 

 synizesis to tetrad formation of the pollen mother-cells. In some cases 

 the nuclei retaining their original features protrude a small portion 

 of their substance by means of a fine connection, while in others the 

 nuclear substance of one cell shows an appearance as if it penetrated 

 like a ribbon through several other cells generally along the long 



