236 BOTANICAL GAZETTE [ocropER 
to become parts of a larger mass. That this fusion did not 
involve a fusion of their nuclei cannot be considered as altering 
the result so far as the question of individuality is concerned. 
Where sexual cells fuse and their nuclei unite there is no ques- 
tion that the resulting fertilized egg is a single cell. If, as 
Hacker (2) has shown is the case in Cyclops, the pronuclei 
remain distinct through the early cleavage stages of the egg, this 
cannot be taken as evidence that the two nucleated bodies thus 
produced are not single cells rather than the equivalents of 
tissues. These binucleated cells, functionally and morphologi- 
cally considered, are the equivalents of the later cells of the 
‘ Cyclops which appear with a single nucleus. The conclusion 
must be, as I have already pointed out, that the individuality of 
the cell is independent of the number of nuclei which it contains. 
Hertwig argues for the potential equivalence of multinucleated 
cells and tissues. The word potential here of course may mean 
much or little. In support of his view he urges the case of the 
insect egg, whose nucleus divides to form hundreds of daughter 
nuclei before cleavage begins. Later the multinucleated yolk 
mass is by cell division separated into a blastoderm of as mam) 
cells as there were nuclei present. It is quite plain, says Hert 
wig, that the apparently simple egg could not with a single 
stroke, as it were, have become a multicellular organism. he 
question here, of course, is how great a change is involved in 
transition from the one-celled to the many-celled condition, 
on this point it is interesting to note that up to the stage wns 
cell division takes place in the insect egg there has been 9° we 
ble differentiation of embryonic structures in the egg- The a t 
division simply transforms the one cell into a mass of equivalem 
cells, and this need hardly be considered as a change too of 
to be due entirely to the cleavage process. The relation 
multinucleated and uninucleated cells is well shown i” the ee 
fact that: the visible differentiation of the insect embry ost’ 
perhaps from the determination of its axes, which da 
plished even earlier, begins after the division of the eg8 oa 
numerous cells, and not while it remains a single cell, althous™ 
the 
and 
