402 



HISTOLOGY 



producing discharge. Many other mammals produce fluids by very 



similar structures, which are attractive or repulsive. The musk ox, 



bat, etc., show these organs. 



The Odoriferous Glands of the "Stink-pot" Turtle. Among the 



reptiles are some that are offensive to the smell. One of such is the com- 



., 7 . mon stinking turtle of the 



- V' v ; , . eastern United States which, 



when captured or handled 

 roughly, gives off a most 

 disagreeable and offensive 

 odor. To do this it dis- 

 charges drops of an oily fluid 

 from the ducts of two sym- 

 metrically placed glands or 

 sets of glands that are placed 

 just inside of the shell on 

 each side of the body. These 

 glands are developed onto- 

 genetically by invaginations 

 of the integument at the 

 point where the duct opens, 

 and they are evidently lined 

 by a stratified epithelium de- 

 rived from that on the outer 

 integument of the animal (Fig. 

 365). This stratified epithe- 

 lium is constantly proliferat- 

 ing as was also that in the 



FIG. 365. Part of the wall of the stink gland of a 

 turtle, Terrapene odorata. b.c., layer of basal cells; 

 o.c., oil cells lying among the many serous cells; 

 m.s., matured serous cell with dead nuclei and 

 ready to burst; b.o.c., young oil cells on the base; 

 sec., secretion, x 650. 



rump gland in the bird, and 

 as all stratified epithelia are. 

 It is also secreting an oily 

 fluid, but there are minor 

 differences in the manner in 

 which the two kinds of glands 

 do this as well as in the product. In the turtle the stratified nature of 

 the layer is obscured by the fact that there are only two distinct strata, 

 an inner or proximal which represents the basal layer of a stratified 

 epithelium, and an outer or distal stratum of many cells in thickness. 

 The single basal layer is constantly dividing off cells which are pushed 

 into the thick, distal layer of cells and which begin to accumulate the 

 secretion as soon as they become independent of the basal layer. 



The secretion appears in a single vacuole on the distal cytoplasm of 

 the cell, and this vacuole enlarges and swells the cell to very many times 



