420 THOS. H. MONTGOMERY jr., 
dermis, perhaps becoming less abundant posteriorly. They vary con- 
siderably in size, but none attain the volume of the giant cells of the 
nerve cord. 
These nerve cells are most characteristic of the dorsal area of 
the hypodermis of the trunk. 
Motor nerve elements. The chromophilic nerve cells of the 
central nervous system being apparently chiefly sensory in function, 
the chromophobic nerve cells, those of the central nervous system as 
well as those of the hypodermis, may be considered the motor and 
visceral elements. Within the central nervous system their processes, 
the chromophobic fibres, can be seen on suitably stained preparations, 
but it is very difficult to follow such pale-staining fibres to the peri- 
phery. When the hypodermis is destained sufficiently to show the 
chromophilic fibres sharply, the chromophobic fibres appear too pale 
to be easily seen. Yet it is not allowable to suppose that these 
chromophobic fibres are limited to the central nervous system, they 
must pass to the periphery, and in all probability by way of the neural 
lamella as do the chromophilic fibres. I have been unable to satis- 
factory determine the presence of chromophobic fibres within the 
neural lamella. But in the hypodermis along one of the chromophilic 
fibres which has entered it and there bent to one side, may frequently 
be seen a clear line of even diameter. Such clear lines may represent 
chromophobic nerve fibres which have penetrated into the hypodermis 
‘from the neural lamella. What would speak for this interpretation is 
the fact that within the nerve cord chromophobic and chromophilic 
nerve fibres are to be seen associated in pairs, so close is the con- 
nection that the larger chromophobic fibre sometimes appears to en- 
close the smaller chromophilic one (though the enclosure is probably 
an optical illusion). Now since the two kinds of nerve fibres are 
present together in the central nervous system, it is also probable that 
they pass into the hypodermis together. But with no stain, not even 
with thionin, could they be clearly seen in the hypodermis except as 
the clear lines above indicated. It is probable that the musculature 
of the body wall derives their innervation from such chromophobic 
nerve elements. 
The chromophobic cells which occur in the hypodermis are 
structurally like those in the central nervous system. The course of 
their fibres could be followed, however, for only short distances. ‘They 
lie very close to the musculature, and perhaps innervate it; or they 
may send processes into the mesenteries to innervate the genital organs. 
