M. Koidzumi 
249 
tudinal strands of deeply stainable substance are observed surrounding the 
columnar core, corresponding to the contents of the axial core in T. agilis. 
At the anterior end, there is no structure corresponding to the knob in 
T. agilis; and there is either only a ring of deeply stainable substance at the 
tip, or else the strands are simply united together at the anterior end. The 
descriptions of the layers surrounding the axial core, of the wall of the bell, 
and of the flagella, given by previous authors, are also diversified. According 
to Porter, the inner layer of the bell is marked with fine lines perpendicular 
to the surface of the body wall, and he took these lines to be traces of tra¬ 
versing flagella. 
Grassi’s statements are, to me, very confusing. He describes several 
different appearances seen by him, and does not give any interpretations to 
reconcile his diverse observations. His opinion seems, however, to be as 
follows. The inner layer is liquid, and the basal granules of the flagella are 
found at the base of this layer, situated on longitudinal ridges lying directly 
under it. In some of his figures, the ridges are shown as forming a distinct 
layer. According to him, the flagella are sometimes provided with a node or 
granule at the outer boundary of the layer. Fran 9 a described the flagella as 
arising from the surface of the axial core; those of the nipple from the 
mushroom-shaped body and those of the bell from the disk-like part. A 
differentiation into layers, both in the nipple and in the bell, seems not to be 
recognized by him; but the existence of such a differentiation cannot be 
doubted. The body wall of T. campanula is figured by Kofoid and Swezy 
(1919) in various ways and their descriptions are not easy to understand; 
but, according to Professor Kofoid’s personal explanation—which he kindlv 
gave me in London—the wall of the bell consists of four layers. The flagella 
arise at the outer boundary of the innermost layer (drawn homogeneous in 
some figures and granular in others), and each flagellum has a node or granule 
at the middle of the portion embedded in the body wall. The outer part of 
the body wall, traversed by the flagella, is divided by an alveolar layer into 
outer and middle layers. 
There are thus many points of disagreement among the statements of 
previous authors, and between theirs and mine; and I cannot but doubt the 
accuracy of their observations. It will be worthy of mention, here, that some 
of the above views were founded upon observations made on material fixed 
and cut into sections, which I believe, from my own experience, are apt to 
lead us to erroneous results. The space encircling the base of the nipple is 
described by Grassi, and Kofoid and Swezy, as rather spacious. But it is 
usually a narrow slit in my organisms, and it was only in specimens badly 
fixed or cut into sections that I found it wide and distinct. 
In the posterior region, the body wall is not thick, though it is fairly 
rigid and stains rather deeply. No clear layer corresponding to the inner 
layer of the anterior region is here recognizable. 
The endoplasm is finely granular, homogeneous, and appears slightly grey 
