489 
Nuclear Division in the Hepaticae. 
invalidate the general rule that the number of the chromo- 
somes is normally constant Cases are known both in plants 
and in animals of a diminished or increased number occurring 
as exceptional cases. Of course there are the further instances 
of the antipodal cells of Lilies described by Guignard, and of 
the late endosperm cells in Pinus mentioned by Dixon ; these, 
however, occur in declining tissues, and are therefore perhaps 
not to be regarded as on the same line as variations occurring 
in the first stages in the existence of the organism. 
Aneura multifid a. 
The process of spore-formation in this plant recalls that 
observed in Fossonibronia , except that the number of the 
chromosomes are more numerous. A very well-marked 
quadripolar spindle is seen during the earlier stages, and 
the end of each arm, which protrudes into the rather shallow 
lobes of the mother-cell, is occupied by an exceedingly well- 
marked centrosphere, with exquisite radiations extending 
from it. The division of the nucleus is successive, and an 
interval of rest occurs between the first and second division. 
These two mitoses are, so far as I could determine the point, 
exactly alike, and when seen in the equatorial plate the 
chromosomes often exhibit the ring form with greater or less 
distinctness (see Fig. 36). It would be very desirable to 
repeat these observations on Aneura pinguis, of which I have 
for two years endeavoured to secure sufficient abundance of 
fruiting specimens, hitherto without success. The nuclei 
are very much larger in this species, and are in every way 
better fitted for accurate and close observation than is the 
case with those of A. multifida. In the latter plant it was 
clearly seen that the number of the chromosomes is reduced 
to one half between the last archesporial and the first spore- 
mother-cell division, and also that the appearance of the 
chromosomes in the two cases respectively is very different, 
just as has already been mentioned for other genera. 
Fegatella coniea. 
The characters of the spore-formation as presented by this 
