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(d) Comparative Review. — From a brief summary and comparison of 
the observations on the origin and morphology of the intermediate cell- 
mass in Teleosts, it appears that Wenckebach’s ('86, p. 246) account for 
Belone differs materially from Oellacher's (’72) for the Brook Trout, as 
well as from Ziegler's (’82) observations upon the Salmon and my own 
on Fundulus; that is, he did not observe its true lateral origin, or any 
modification of it in different regions of the trunk. If Wenckebach’s 
account of the origin of this structure is correct and complete, Belone is 
an exception among Bony Fishes, and differs materially, in this point, from 
other groups of Vertebrates, As has been stated (p. 113), Wenckebach 
refers the origin of the intermediate cell-mass to individual cells, which 
migrate from the protovertebree to a position under the chorda, and here 
proliferate and form the compact cord of cells which may be designated 
the axial portion of the intermediate cell-mass. My observations on 
Fundulus agree in general with Oellacher’s for the Brook Trout, so 
far as he describes the structure. I have seen no evidence in Fun- 
dulas in support of the theory toward which Ziegler inclines, namely, 
that the intermediate cell-mass retains histological connection with the 
protovertebræ. 
Ziegler’s observations on his “formative tissue” in the Salmon, and 
his study of the relation between it and the intermediate cell-mass, are 
based on relatively older stages than those in which I have observed the 
origin of the intermediate cell-mass in Fundulus. The identity of the 
intermediate cell-mass and the formative tissue arising from the protover- 
tebræ, or even an intimate relation between the two in Fundulus, must 
be questioned when we consider the fact that the intermediate cell-mass 
