STRUCTURE AND DEVELORMENT OP REISSNER’s FIBRIC. 17 
occurring on the general ventricular (ependymal) epithelium, 
whereas what Dendy said was really precisely the opposite. 
Ue then goes on to say — “ I believe that there are no cilia iu 
tlie grooves.” I shall show later that the grooves are 
abundantly ciliated. 
He, again and more emphatically, on the strength appa- 
rently of an examination of a single series of sections 
through the tail of Petromyzon marinus, controverts 
(’04, p. 160) the account given by Studnicka (’99) of the 
endingof the fibre posteriorly in Petromyzon and Myxine, 
and appears to be wholly unaware of Studnicka’s reply (’00) 
to his earlier criticism. From his own account and figure 
(’04, PI. I, fig. 8) it is evident that Sargent himself had 
not seen the actual termination of the fibre in the sinus 
terminal is of the adult lamprey. 
In this paper, also, he institutes a comparison between 
Reissner’s fibre and the large (Dachkern) cells from which 
he says it arises, and the giant fibres and cells of Amphioxus 
and Chmtopoda (p. 158), and concludes — “It is possible 
that Reissjier’s fibre and the cells which give rise 
to it are represented by elements in the invertebrate nervous 
sy.stem.” 
'J’o avoid repetition it will be desirable to postpone a more 
detailed criticism of Sargent’s general results, and also of 
those of Houser, until after I have given a general account 
of what I believe to be the true relationships of the parts 
concerned. Certain other more special criticisms will follow 
the description of each class. 
At the end of his memoir Sargent announced that a second 
part, dealing with the higher vertebrates, was already well 
advanced (June, 1904), and would, it was hoped, appear in 
about a year. This has not yet been published, but in the 
interval that has since elapsed several references to this 
subject have appeared in the works of other authors. 
Kolrner (’05), in an elaborate paj)er on the spinal cord of 
.\mmocoetes, ])ublished iu the following year, records the 
finding of Reissuer’s fibre in the caualis centralis of that 
VOl,. 58, I’AKT 1. NKW SIOHIKS. 2 
