776 The American Naturalist. [September, 
supporting cells and the cuticula from the enveloping cells of 
the dermal sense organs. Inthe epithelium around the sense 
bud both Henle’s and Huxley’s layers may be seen forming 
the inner root sheath as in the hair; while the connective 
tissue envelope forms a sense bud follicle just as the same layer 
forms the hair follicle. Even a papilla is frequently present 
in many Amphibia; (e. g., Cryptobranchus), containing 4 
capillary network; but since the hair has lost its sensory func- 
tion the axial nerve of the sense organ has degenerated. 
We cannot go into the wealth of fact and comparison which 
Maurer has advanced in support of his position (which we may ' 
say in passing, has won the acceptance of Gegenbaur) but some 
of his statements and conclusions should be summarized here. 
According to Maurer two types of organs are developed from 
the integument. The epidermoid organs are those structures 
which both phylogeneti-. 
q ; 
Ba TE NEET ETA cally and ontogenetically 
OR CNG oem € arise exclusively from the 
Sree: QE we 2 epidermis, and to which 
G. 14.—Section through the liest wen ai oniy Se 
stage of a developing sense gadis of Triton when necessity for protec: 
prises Care ee A . the pree e tion or nourishment arises. 
its cells ‘becoming columnar, the Tak sues Here belong the tegumen- 
Peon shold be aada nit t COM tary sense organs of the 
lower vertebrates as We 
as the “pearl organs” of the Teleosts, the femoral pores of the 
lizards, dermal glands and lastly the hairs of the Mammalia. 
Integumental organs in the narrower sense are those which 
have their first foundation in an alteration of the corium and 
always arise as an elevation of that layer, although the opr 
dermis may be associated with it later and may secondarily 
acquire great prominence. Here belong the scales of fishes 
and reptiles, the feathers of birds and certain mammalian 
scales. 
From this statement it is clear, if ontogeny be a test, that 
hair and feathers, are totally different structures; for as ws 
have seen the development of hair begins with the epiderm!s; 
that of feathers as clearly with the dermis. 
