108 THE BOTANICAJj MAGAZINE. H™. xxxvi. No. 429. 



small part of it is extruded is a possible interpretation, but it seems 

 hard to account for the fact that such figures, for instance Fig. 4 

 and Fig. 5, in which the greater part of nuclear substances are ex- 

 truded or even the nuclei are considerably deformed, are the normal 

 phases of the cell phenomena. When the cells of ovary wall, nucellus 

 and loculus are examined with care, it is often found that the nucleus 

 alone or the whole contents of the cell lie excentrically in the cell, as 

 if they were forced to do so by some external agent, but the extrusion 

 phenomena are seldom observed, a fact which shows that extrusion 

 occurs with difficulty in the somatic cells. This may probably suggest 

 the lack of extrusion between the embryosac mother-cell and the cells 

 which compactly surround it. The inconspicuous plasma-connection 

 between them will also help the suggestion. In the pollen- and 

 embryosac mother-cells with the nuclei in the metaphasic stage, the 

 plasmolysis and the chromosomes lumped in a mass are very often 

 found. And such lumps are sometimes pressed towards one side of 

 the cell. This may be caused by a faulty fixation. An extremely 

 contracted state of the contents of the mother-cell nuclei is frequently 

 observed, which seems to point to the opinion of Schaffner and 

 others that synizesis is an artifact (17, 18, 19). From the observations 

 in Iris japonica it seems that the effect, direct or indirect, of the 

 fixing fluid is one of the main categories of the external injuries. 

 Various appearances of the extruded bodies in various stages of the 

 dividing nucleus, which are viewed by Digby, Gates and others as a 

 continuous process, may probably be interpreted as various effects of 

 the fixatives. And if this phenomenon be an artifact caused by the 

 faulty fixation or some other external influence it will not have any 

 importance on the heredity, the life-cycle, or the individuality of 

 chromosomes, and probably it can not be considered as a normal 

 phase in meiotic stages. 



Lastly a few words will be added regarding synizesis and the 

 extrusion. In the pollen mother-cells of Iris japonica there are cases 

 where the synizetic mass can easily be recognized, while in others 

 owing to the extreme deformation of the nucleus, it is not recognized. 

 In the former cases it is of interest that the direction of the con- 

 traction of the nuclear contents appears to coincide with that of the 

 extrusion of the same nucleus, and that the nucleus itself seems to be 

 obliged to extrude its part by certain external force rather than by 

 its autonomy. 



