90 HISTOLOIIY OF THE I'OIS! )\-( JLA NDS OF BUFO AGUA. 



Km. 4. Vertical sections through the dud of a mature poison-gland celloidin-iron heniatoxylin. Photomicrograph. 



1'JO. Tn slum the manner of glandular regeneration. The gland-duet i.s shown emptying into a pit or 

 foveolus on the skin suiface. The dui-t. is surrounded by a ring of young glands which have budded off from 

 tin- duct rpithi'lium. The section is cut directly through the duct of one of these young glands, the lumen 

 of \\ hich can be seen communicating with the lumen of the duct leading into the mature acinus. The young 

 glands are embedded in the compact layer of the cutis, but they, as well as the duct of the old gland, are 

 UrroUtlded by connective tissue derived from and directly continuous with the outer loose layer. The 

 lining epithelium of these young poison-glands is still intact and the secretion has not yet begun to form. 



Fit. ."> Vertical section through the parotid gland showing young poison-glands. Photomicrograph. X120. The 

 young glands in t his section are of the adrenalin-containing variety and are in the earliest stages of secretory 

 activity. The swelling of the glandular epithelium preparatory to its disintegration to form the granular 

 secret ion has just begun in some and is well under way in otheis. The small gland nearest the surface 

 epithelium is the youngest stage. On one side of the acinus the gland epithelium is still low cuboidal in type, 

 while on (lie other side the cells have swollen and have become vacuolated. The same change has occurred 

 in the alveolar fundus of the left-hand gland of the pair below, while its fellow on the right shows swelling 

 of the entire epithelium with beginning vacuolation and disintegration. 



KM:, (i. V^rUcal section through the parotid region. Celloidin-iron hematoxylin stain. Photomicrograph. X100. 

 A young poison-gland which has grown down from the surface epithelium through the compact stratum of 

 the derma. The plasm of the gland epithelium has broken down entiiely and the gland is now merely a 

 sac filled with a granular secretion and lined by naked nuclei which are seen in groups along the inner side 

 of the gland-wall. The epithelium of the collar and duct is only two cells thick. There is no trace of any 

 chromafhn material in the secretion of such a gland. Already a small gland and duct have budded off from 

 the duct of the larger one and two of the epithelial cells of the tiny sac have swollen and taken on a high 

 columnar form preparatory to the evolution of secretion. 



PLATE II. 



IMC. 7. Section through the acinus and duct of a mature poison-gland. Fixed in formol bichromate-eelloidin-Mal- 

 lorv's stain. Kreehand drawing, about X100. The secretion in the lumen of this gland shows the yellow 

 color of a brilliantly positive chromatlin reaction. The homogeneous fluid about the periphery of the gland 

 acinus gives the reaction most strikingly, but in this gland, which is evidently an old our, the epinephrin- 

 containing fluid has diffused through the granular material in the center of the acinu> anil the entire secretion 

 contains some of the chromate-reducing material (epinephrin). This gland h:i, :d>oni its duet a number of 

 young glands growing downward into the inner loose layer of the cutis. The .stratum compact um cut is appears 

 as a dense blue mass. This particular section shows very \\ell the dragging down of the corial nielanophores 

 by the gland as it carries with it, in its downward growth, a sheath from t he outer loose layer of the cutis. 



Fit:. S. High-power drawing of the wall of a mature poison-sac. Tissue fixed in formol biehromate-celloidin-hema- 

 toxylin and eosin. Freehand drawing. Leitz ocular No. 3 and objective 7. Tube length 160 mm.; about 

 X400. The gland-wall is surrounded by a loose network of very tine fibers derived from the outer loose 

 stratum of the corium (t). The naked nuclei lining the gland-sac are covered over by the deeply stained 

 chromaphi) secretion (a. s.) which lies immediately within the gland-wall. The reticular appearance of the 

 secretion lying next the muscle is probably due to precipitation of albuminous material during fixation. 

 The secretion has also injected the spaces between the fibers of the circular muscle layer about the gland (;.) 

 and shows the arrangement of the matrix in which the fibers are embedded. 



I'Y:. II. Section of a sympathetic ganglion of Bufo agua. Fixation, staining, and treatment as in fig. S. This section 

 shows cords of chromatfin cells with small, deeply-staining nuclei and granular cytoplasm (CY.) sharply 

 separated by broad connective-tissue bands from the masses of large ganglion cells (gang.) ami nerve fi!:>:-;.-.. 



Fit:. 10. Section of the adrenal body of Bufo. Tissue fixed in formol-bichromate. Frozen section counterstained with 

 Sudan III. Drawn freehand. Zeiss ocular Xo. 5 ami objective 16 mm. Tube length 160 mm. About 

 X300. This section shows the typical adrenal body of the Anura. The interrenal cells are laden with 

 sudanophil lipoid. They do not form any definite pattern with the cords of adrenal substance (a. m.), but 

 I lie two cell-types mingle. The green color of the chromaphil material in the adrenal substance results from 

 :m attempt to stain these sections with (iiemsa's stain. 



