252 BOTANICAL GAZETTE [APRIL 
even in part as he does, the idea of the contractility of the secondary 
linin-fibrils, in addition to the above theory, since an automatic move- 
ment such as he conceives to take place should be regarded as an 
amoeboid movement in response to chemotropic stimuli. WILSON 
(:O1, p. 575) also regards the chromatin as ‘a liquid substance which 
may be absorbed or given off by an achromatic basis such as plastin 
or linin, and may thus flow from one part of the nucleus to the other.”’ 
The latter author appears to adopt to a certain extent the ideas of 
BUTSCHLI (’92), in that in his studies on Toxopneustes he has become 
thoroughly convinced that the astral radiations are in part the result 
of centripetal currents, or diffusion-currents, of hyaloplasm converg- 
ing on the centrosphere. 
While it is quite possible that the chromatin in Empusa is a liquid 
substance which may flow or diffuse about through an achromatic 
linin basis, as WILSON suggests, this, in my opinion, does not preclude 
the idea of a contractile linin substance serving as the mechanism of 
mitotic division. I must say, however, that while entirely convincing 
evidence is lacking that the primitive mitosis in Empusa is accom- 
plished by means of a contraction and a growth of the fibrillar, kino- 
plasmic radiations, there is, on the other hand, even less evidence in 
favor of other theories; for example, that the movement of the chro- 
matin is automatic, due to chemotropic forces which are supposed to 
emanate from the centers; or that this movement is due to diffusion- 
currents induced by the chemism active at the centers; or that it 
results from magnetic or electrostatic forces, an idea which has been 
recently revived by LILLIE (:05). 
In the primitive mitotic division characteristic of Empusa, we see 
but little resemblance to the corresponding process as described for 
other low plants. In all these cases, even in the Myxomycetes 
(HARPER, :00), a well-defined spindle and chromosome, and an 
equatorial arrangement of the chromatin may be observed. It is 
apparently very common among the thallophytes that the nuclear 
cavity and membrane persist during a large part of the mitotic pro- 
cesses; see, for example, figures of Erysiphe (HARPER, ’97), of Albugo 
(STEVENS, :01), of Dictyota (Mortrer, :00). But in all of those 
thallophytes in which centrosomes occur, the latter are extra- and 
not iira-nuclear bodies. Empusa is therefore in this respect unique 
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