Nuclear Phenomena in the Smuts. 
495 
gation is a mutual devouring of each other by egg and sperm 
is interesting and perhaps gains an added element of proba¬ 
bility. That this does not, however, afford a complete explana¬ 
tion of cell fusions is shown by the case of the conidial fusions 
of the anther smut, where neither cell devours the other but 
each maintains its individuality and germinates independently. 
In this case we must assume that the fusion produces some 
change in the condition of the protoplasm whereby its metabo¬ 
lism is increased; and, perhaps also, it becomes more resistant 
to unfavorable external conditions. 
For completeness may be mentioned the fusion of cells end to 
end to form the vessels, tracheae, of the higher plants and the 
fusion to form laticiferous ducts in certain cases. These cases 
are however quite different from the others mentioned, in that 
they occur in cells not destined to further development by di¬ 
vision, and in the first case at least are accompanied by the 
death of the cells. 
In still a further and quite interesting category may be men¬ 
tioned the union of the swarms spores of slime moulds to form 
plasmodia. Here the union consists in the formation of a larger 
amoeboid mass with a common plasma membrane by the union 
of numbers of smaller amoeboid cells. It is in its origin, doubt¬ 
less, a preparation for spore formation and has been developed 
from the habit of the Acrasieae to come together to form stalked 
spore fruits, although in these latter forms the swarm spores 
pass through their entire vegetative existence as distinct bod¬ 
ies. Plasmodium formation would then be an occurrence at an 
earlier stage and more completely of the aggregation of cells 
which in Dictyostelium , for example, occurs at the time of 
uiting. What the advantage of this union is cannot be pointed 
out with certainty, except that it brings and keeps the cells to¬ 
gether so as to prevent their becoming too widely scattered be¬ 
fore the time of fruiting. It perhaps also secures a more even 
distribution of food among all the cells that are later to combine 
to a single fruit body. 
If we look now for the significance of these various types of 
cell fusions, it seems plain that in none of them do we have any¬ 
thing that is comparable to sexual fusions. The nuclear fusion 
