!8 BOTANICAL GAZETTE [july 



at various angles to each other. Spindle formation is the same as for 

 the heterotypic mitosis, except that the spindles are smaller. In 

 regard to the chromatin, suffice it at present to say that the chromo- 

 somes of the homotypic prophase show the same general types and 

 are often identical in appearance with those of the heterotypic telo- 

 phase. There can be no doubt that the bivalent bodies which appear 

 on the homotypic spindle are the same bodies that were present in the 

 telophase of the heterotypic. Fig. 41 shows an early anaphase of the 

 second mitosis, the members of each pair having just separated. One 

 of the small nucleoli appears by one of the spindles. 



IRREGULARITIES 



In fig. 39 spindle fibers are seen in the cytoplasm by the side of the 

 spindle in anaphase. This may be connected with a condition which 

 is illustrated in fig. 40. Six such cases were observed in which a 

 regular spindle occurred at the side of the mother cell instead of 

 between the daughter nuclei, after the partial or complete disappear- 

 ance of the heterotypic spindle. Some of these cases were in the telo- 

 phase of the heterotypic spindle (fig. 40) ; others were in the prophase 

 of the homotypic. In these cases the spindles were regularly formed 

 and rather sharp-pointed and occupied the same position at the side 

 of the cell; of course they contained no chromosomes. The method 

 of their origin is unknown, but it seems probable that they are con- 

 nected with the condition observed in fig. 39. Mother cells which 

 probably indicate an intermediate condition, in which irregularly 

 arranged fibers were found at the side of the cell, were occasionally 

 observed. They may merely indicate a persistence of the kinoplasm 

 of the heterotypic spindle after its function has ceased, but their 

 structure appeared remarkably definite in most of the cases observed. 

 A single case of extra nuclei in the pollen tetrad was observed in 

 O. rubrinervis. These have been previously described in O. lata 

 (11), where they are common occurrences in connection with pollen 

 degeneration. The single case observed in O. rubrinervis is sketched 

 in fig. 42. Two small nuclei are present in addition to the four 

 larger ones composing the tetrad. The nuclei had passed too far 

 into the resting condition to count the chromosomes in each 

 nucleus. 



