Capillitinm in Certain Myxomycetes. 1 1 
tainly a striking similarity between the astral rays which are formed by the 
flow of a differentiated substance from the centrosome outwards through the 
cytoplasm and the fibrillar cilia formed from a blepharoplast on the surface 
of a cell. In the case of the antherozoids of Ferns and Cycads it has been 
shown beyond question that the cilia first push out within the cytoplasm, 
and continue their growth through the plasma membrane into the sur- 
rounding medium. That kinoplasmic fibrils may be formed as streaming 
material, and later become contractile elements, is not inconsistent with any 
known facts, and seems to be clearly suggested by the mass of data which 
has accumulated as to the relations of centrosomes, blepharoplasts, and the 
fibrillar elements developed about them. It seems possible now to include 
in the category of central spindle fibres, astral rays as seen in free cell- 
formation and cilia as the outgrowths of blepharoplasts, the further type of 
radial fibrils about the capillitial vacuoles, for which the evidence, both 
from their appearance and their probable functions, so strongly favours the 
view that they represent streams of specially active formative materials. 
Faull ( 10 , 11 ) seems to have failed to understand the account of the 
movements of the astral rays in the formation of the ascospore just referred 
to, for the description given ( 21 ) is in no way susceptible of the interpretation 
which he puts upon it. Nothing is said of a simultaneous movement of all 
the rays of the aster, in which each would keep its. relative position to all 
the others. The figures give no evidence for such a movement. On the 
other hand, it is distinctly specified that the folding-over movement begins 
with the rays which extend in the line of the axis of the nuclear beak, and 
that these rays thus come to crowd upon those next to them. The cone- 
shaped opening in the aster shows that the movement begins in this way, 
and that the crowding and fusing which result from this movement accumu- 
late the material for a continuous plasma membrane. Faull (11) admits 
that the plasma membrane of the spore forms from the centrosome outwards. 
Admitting this, his own figures give good evidence against his words that 
the recurved rays and not an imaginary limiting layer, the precursor of the 
spore membrane, determine the location of and form the boundary for the 
spore. The relative positions of the rays in his Figs. 6 % and 63 , PI. XL, 
certainly suggest that at least some of them have moved. 
A further type of fibrillar structures which may also be due to cyto- 
plasmic streaming are Nemec’s (38) longitudinal fibrillar systems in the 
cells of root-tips, to which he assigns the function of transmitting stimuli 
from the perceptive to the motor region. Haberlandt (18) has attempted to 
show that such fibrillar structures are due to streaming on the basis of their 
general resemblance to the appearances, many times described, for streaming 
protoplasm, and the fact that he was able to observe streaming movement 
in the central protoplasmic strand of root-tip cells. Unpublished observa- 
tions by Marquette, which we are allowed to report, show that in the living 
