DEVELOPMENT OF THE GAPE SPECIES OF PERIPATUS. 193 
part of the nucleus? Is it the spongework or is it the deeply- 
staining parts of the spongework? A comparison of figs. 
2 and 3, in which the amount of deeply-staining matter is so 
different, favours the first view, viz. that the essential part of 
the nucleus is the spongework ; while on the other hand the 
facts about the male and female pronuclei described on p. 190 
are in favour of the second view, viz. that the deeply-stain- 
ing matter is the all important part of the nucleus. For in 
these cases we have astage in which the nucleus is represented 
only by a mass of deeply-staining matter, which subsequently 
enters into a more complicated relation with the surrounding 
reticulum in order to give rise to the vesicular form of nucleus 
ordinarily found. 
It is, therefore, impossible to decide which, if either, of these 
two views is correct. Indeed, it seems useless to discuss the 
matter except in connection with the functions of the nucleus. 
The nucleus appears to be a kind of co-ordinating centre for a 
given mass of protoplasm, and as such it may be looked upon 
as a centre from which force emanates. If this is so, need it 
have any essential structure beyond being the point to which 
all the strings of the protoplasmic spongework converge—iu 
other words, such a structure as that possessed by the two poles 
of the spindle in Pl. XII, fig. 11? Is it not conceivable that 
a centre of this kind is necessary to the well-being of all 
masses of protoplasm beyond a certain size; and thatif they do 
not derive such a centre from a pre-existing centre they acquire 
one de novo? May not the complexity of structure which 
the nucleus ordinarily presents be a secondary feature, and 
indicative of a higher organization of the protoplasmic mass 
containing it? Or, to put the matter in another way, is the 
complicated structure of the nucleus as ordinarily seen the 
cause or the result of the peculiar properties of the nucleus ? 
Without venturing to put forward any hypothesis on this 
difficult and obscure matter, I may draw attention toa fact 
which favours the view that the nucleus of any protoplasmic 
mass is primarily a central and complicated nodal point to 
which the strands of the spongework mainly converge, and that 
