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233 
filament, is lost in the following manner. The chromatin filament 
first gradually disappears, but before this change is complete the 
rhizoplast has passed backward in the cytopharynx, drawing the 
flagellum after it. By this means the free part of the flagellum is 
shortened. It constitutes an active shortening of the flagellum. 
Prowazek has previously described this process in the flagellum of 
H. muscae domesticae. The chromatin filament in the flagellum is then 
absorbed centripetally, so that in some cells only the chromatin of the 
intracellular part remains, and, as this process takes place, the proto¬ 
plasmic basis of the flagellum is retracted pari passu. The protoplasmic 
basis does not remain when the chromatin has been absorbed. This 
constitutes a passive shortening of the flagellum. 
These observations on the structure and changes in the flagellum 
seem to show that the chromatin is devoted to sustaining the flagellum 
in a filamentous form, which the protoplasm surrounding it has no power 
per se of doing. 
The function of movement is, we think, subserved by the proto¬ 
plasmic basis of the flagellum. It is obvious that the protoplasmic 
basis is homologous to the undulating membrane of Grithidia and 
Trypanosoma, although it has been seen that when the flagellum is 
drawn up into the cell by the posterior movement of the blepharoplast 
it does not form an undulating membrane as such but remains within 
the endoplasm. The undulating membranes of the Trypanosomatidae 
contain myonemes, so that it is most probable that the function of 
movement is subserved by the protoplasmic basis of the flagellum. 
The staining reaction of the protoplasmic basis, or of the Mnetoplasm, 
as I propose it be called, is the same as the endoplasm of the cell, and 
is obviously derived from it, so that it is interesting to see that the more 
hyaloplastic constituents of the cell are employed for the function of 
movement. 
Ghromidia. It has been seen how the size and number of the 
chromidia vary inversely with the amount of chromatin present in 
the nucleus and other organella. There can therefore be little doubt 
that they represent the supply of chromatin for the use of the cell. 
Swellengrebel has shown that they do not consist of chromatin itself, 
but of a slightly altered substance named ‘ volutin.’ They probably 
are concerned in the following manner. When the parasites are under¬ 
going involution the chromatin in the organella is dissolved by the 
protoplasm and circulates in the cell, and is then taken up by certain 
plastids, and resecreted as ‘ volutin,’ in the form of the chromidia. 
