324 SCIENCE PROGRESS. 



Hitherto these differences in the structure of the spheres 

 have been implicitly, if not explicitly, regarded as indications 

 of an indefinite variation in these organs between cell and 

 cell, but if the facts be grouped together (as above) it be- 

 comes quite clear that there is some sort of method under- 

 lying the apparent meaningless variety of sphere formation, 

 and that the modifications of these structures have probably 

 as real a morphological significance as any grosser features 

 of anatomy. At the same time, however, the fact should 

 not be lost sight of, that, although we may thus split up a 

 cell into zones having different potential destinies with 

 respect to the structures which arise out of them, it does 

 not follow that similar structures always arise from similar 

 cellular zones. In fact this capacity of forming similar 

 things from different sources which cells possess, constitutes 

 an admirable example of the truth contained in Whitman's 

 aphorism, '' Organisation precedes cell formation " 1 



It is thus sufficiently apparent, from existing observations 

 on the constitution of the spheres in tissue cells, firstly, that 

 the archoplasm is not always present in them, and secondly, 

 that where this structure does exist it is not necessarily 

 persistent through successive cellular generations. It 

 consequently follows, that the only portion of the sphere 

 which can still lay any claim to persistence, or to a place 



1 The tendency apparent throughout the earlier literature, to regard the 

 nebenkern as a sort of transmissible entity, has probably been the uncon- 

 scious outcome of the fact that the earlier investigations were almost 

 exclusively confined to cells in which the sphere is compound, and in 

 which consequently there is an archoplasmic spindle formation. 



There is perhaps nothing anomalous in the apparent indifference with 

 which the spindle originates either as an intra- or an extra-nuclear structure, 

 for it seems to me merely one mode of expressing what appears to be a 

 fact, i.e., that the kinoplasm (archoplasm) can take up either an intra- or 

 extra-nuclear position. Nor is the dismembered condition of the sphere, 

 to which I have alluded, at all an isolated peculiarity, as Lauterborn's 

 figures of the separated centrosomes and archoplasm in diatoms will show 

 (24). As Ischikawa very justly remarks, with the rather marked exception 

 of the particular animal (Noctiluca) with which he deals, R. Hertwig's 

 supposition (25) that the kinoplasm (archoplasm) of the Protozoa is intra- 

 nuclear while that of the Metazoa is extra-nuclear, appears to have some 

 foundation in fact. 



