374 
D. Carruthers 
Of the plants mentioned above, the course of events in Hyacinthns 
approximates most closely to that described in Vicia by Fraser and 
Shell (’ll). The chromosomes put out blunt lateral processes, and at 
the same time split down the centre at these points to form the well- 
known diamond-shaped areas. In Hyacinthus the most marked difference 
from Vicia at this stage is in the formation of a pre-reticular sph'eme, 
the ehromosomes uniting end to end, so that the process of formation 
of the reticulum from the daughter chromosomes is the exact reverse 
of that by which the chromosomes are formed from the reticulum in 
the prophase. 
The resemblance between the two spiremes, if one may so call them, 
is so striking that one is driven to consider whether it may not be of some 
value in the elucidation of the problem of meiosis. If the pre- reticular 
spireme is formed in the last pre-meiotic division, and the spireme in 
the heterotype prophase follows in the normal course, it is difficult to 
see how to attach any interpretation to that “double” spireme other 
than that it is the normal fission occuring in every mitosis. Unfortunately 
it has not yet been possible to investigate this, but it is hoped that 
the work may be completed in the near future, by a study of the pre- 
meiotic and meiotic divisions. 
This explanation of the reconstitution of the daughter nuclei has 
been eontested by Sharp (TO) for Vicia, and by Gates (’12) for Oeno- 
tJiera. The latter holds that no split of any kind is visible until the late 
prophase, and that the chromosomes merelv form a nearly solid mass 
of chromatic material at the poles. Such figures are common in Hyacin- 
thus but have been attributed to bad fixation or staining, since in the 
best nuclei it is possible to see the details of structure in the telophase 
with mueh greater clearness. Sharp (T3) is of the opinion that there 
is no Connection between the aveolization and the fission, a view which 
is also held by Gregoire (’06). In Hyacinthus however there is little 
doubt that the diamond-shaped areas in the telophase correspond to 
those in the prophase spireme, and these to the fission which occurs soon 
afterwards. 
The Segmented Chromosomes. 
The frequent presence of chromosomes which go through the whole 
process of mitosis in two or three segments Supports the idea suggested 
by Fraser and Shell (’ll) that it is not the actual chromosome but 
some smaller portion of the nuclear content which is persistent and in- 
dividual. In Hyacinthus the segments are generally connected by a 
fine thread, although sometimes the chromosome is completely segmented, 
