330 ROY L. MOODIE 
SUGGESTED EXPLANATIONS OF THE INFLUENCE OF THE LATERAL- 
LINE CANALS ON OSTEOGENESIS 
The influence of the lateral-line system is suggested by the 
nature of the ossification around the canals. One explanation 
which may be offered for this association is that the influence 
is a mechanical one due to the presence of the tubular canals, 
which on account of their early appearance, are in a more ad- 
vanced state of development and the colloidal substance? on their 
surfaces earlier attracts the deposition of calcium salts. This 
influence acting in conjunction with capillary and surface phe- 
nomena on the surface of the canals induces the ossification around 
them.. The problem is thus a very complex one and diff.cult to 
understand in its final analysis, since the effects of living material 
on chemical reactions of this nature are little understood. 
The spicules, wavy in outline, are laid down parallel to the 
canals. ‘They look like wavy brown threads. Their irregularity 
is doubtless due to the irregular disposition around the canals 
of the osteoblastic cells between which the threads are deposited. 
The threads are non-crystalline, since they fail to react to polar- 
ized light, and their nature is especially evident on the suborbi- 
tal canal where the threads are shorter (fig. 4). They differ from 
the otoliths which are crystalline cale-spar. 
The deposition of inorganic material in living bodies is of 
course a very widespread phenomenon, and the nature of the 
process has been discussed, in a very interesting manner by 
D’Arey Thompson (17). That the deposition differs in different 
forms of life is evident, as does also the form of the elements. 
The early formation of osseous material in the so-called membrane 
bones of the head is especially comparable throughout the range 
of vertebrates, being very similar in the catfish and the pig. 
’This interpretation has a striking parallel in the field of neuropathology. 
Recently Doctor Hassin has told me of a ease of calcification in a human cere- 
bellum where the calcium gathered in and around the arteries, around whose 
walls a process known as colloid infiltration had gone on. On the masses of 
colloid material the calcium was deposited. The arteries represent inactive 
material, as do the lateral-line canals; the colloidal substance is aggregated 
around the tubular structures on which the calcium is deposited, and in either 
case may give rise to bone. 
