106 THE BOTANICAL MAGAZINE. [Vol. xxxvi. No. 429. 



axis of an anther (Fig. 12). It happens frequently that the nuclei of 

 two, three, or sometimes more, cells unite with each other and then 

 take a form as described in the last case. In some cases the con- 

 nection between the extruded portion and the nucleus from which the 

 former was derived, is kept not by fine thread, but by thick rods or 

 bands which appear not to have crept out through the small pore 

 in the membrane. In Fig. 18 along the protruded portion the cell 

 membrane is seen as if it were pushed. From these facts it is 

 suggested that the extrusion phenomena are not caused by the 

 autonomy of the nucleus concerned, but is the result of mechanical 

 injuries caused by some external action when the nucleus is in a 

 particular physiological condition. 



GENERAL CONSIDERATION 



The extrusion of the nuclear substance in Iris japonica can not 

 probably be attributed to the traumatic effect of cutting or stripping 

 as in the cases of Miehe and others (11, 15, 20). In the present case the 

 whole flower-buds with young stamens, pistil and perianth were im- 

 mersed in a fixative with care so as not to give them any direct injury 

 by the knife. Kornicke says that extrusion is found in the neighbour- 

 hood of the section of the filament in Crocus, but that in the anther 

 there is no extrusion, while on the other hand it is observed in the 

 anther fixed without being separated from the whole flower-bud. 



The influence of temperature is here out of the question, for the 

 materials were collected from the plants grown in a garden and not 

 acted upon by any unusual temperature. 



The external pressure, for example the pressure of the pincette, 

 to which the materials were subjected at the time of fixation is 

 thought possibly as a part of the cause of the extrusion ; for when 

 the flower-buds were brought into the fixing fluids by the aid of 

 pincette, a good many extrusion figures were observed ; while at the 

 second fixing, when the peduncles of the flower-buds were cut by the 

 knife before they were dropped into the fluid, there appeared probably 

 less figures of extrusion than at the first time. 



The interpretation of this phenomenon as the incidence of the 

 subsequent degeneration of the mother-cell (3, 5, 6), though it is an 

 interesting suggestion, appears not to be convincing in my case of Iris 

 japonica. 



Kornicke's interpreting regarding this process in Crocus does 



