378 Harper .— Sexual Reproduction in Pyronema 
similarly contractility and irritability are manifested by 
protoplasm independently of the aggregation of its parts in 
cells. A bit of an amoeba cut off from the parent cell and 
not containing any portion of nuclear material still responds 
to stimuli, is contractile, and creeps about in apparently 
normal fashion. It must be concluded that the liberation of 
energy for motion and the response to external stimuli is 
independent of any interrelation between nucleus and cyto¬ 
plasm, and in the manifestation of all such phenomena the 
uninucleated and multinucleated cells would be at least on an 
equal footing. 
The uninucleated swarm-spore of Oedogonium acts no more 
as a unit in its reactions to light than does the multinucleated 
swarm-spore of Vaucheria . So far as we know the pollen- 
tube with its vegetative nucleus responds to chemical stimuli 
just as does the multinucleated hypha of Mucor. The 
uninucleated conidiophore of Basidiobolus orients itself with 
reference to light-stimuli just as does the multinucleated 
sporangiophore of Pilobolus. 
The metabolism inside the cell in that phase in which food 
is changed into organized material is doubtless dependent, as 
Schenk points out, on the interaction of nucleus and cyto¬ 
plasm. The metabolism of the multinucleated cell is probably 
carried on in connexion with many centres instead of a single 
one, but in this respect the conditions here would not be 
strikingly different from what they are in such cells as are 
found in the spinning-glands of insects in which the single 
nucleus is branched so as to extend into all parts of the 
cell interior ( 24 ). These lining elements of spinning-glands 
cannot certainly be excluded from the category of cells, and, 
so far as the relations of their internal metabolism to their 
nuclei are concerned, they cannot be very different from 
multinucleated cell structures. 
The statement has often been made that the Vaucheria 
filament is a mass of cells which merely lack their partition- 
walls. There is, however, no evidence that the reception of 
food in Vaucheria, its distribution to various parts of the 
