PLATE XXI. 



Fig. 9. — Elastic fibres [el.f.) on surface of gland. Gland wall [e.t.l.) in 

 section indicated; also nuclei of gland cells. The elastic fibres 

 pass through the inner layer of the eorium (i.e. I.). Tanzer's 

 orcein. 'M- 



Fig. 10. — Section through upper pole of gland at one side of the duct, show- 

 ing cut ends of muscle fibres (to./.) and their nuclei (m.n.). 

 From cross section of tail. The nuclei in this figure correspond 

 in position to that shown in PI. XX, Fig. 6, and to the enlarge- 

 ment of the fibres shown in Fig. 8. Mallory's conn, tissue stain . 

 342 



Fig. 11. — Tangential section through wall of gland and the mouth, from 

 frontal section of tail. .Muscle fibres (»«./.) and nuclei [m.n.) 

 shown. Funnel cell [fl.C.) lining duct and some secretion [sec. 

 in lumen of duct [l.d.). Mallory's conn, tissue stain. 342. 



Fig. 12. — Cross section of gland from frontal section of tail, at level of 

 muscle nuclei [m.n.). Compare with Figs. 10 and 11. Van 

 Gieron's stain. 400 



Fig. 13. — Cross section of epidermis at upper pole of poison gland, showing 

 deep lying epidermal cell [ep.m.c.) which contains the con 

 strictor and dilator muscles of the duet. Mallory's conn, tissue 

 342 



Figs. 14 and 15. — Cross sections of duets at level of cell described in Fig. 13, 

 showing constrictor (con. to.) and dilator muscles (dil.m.). In 

 Fig. 14, only the outer ends of the constrictor fibre appear. In 

 both figures are shown the ends of the muscle fibres (to./.) of 

 the glands, in the epidermis, and the connective tissue (c.t.) 

 outside the nuscles. The nucleus of the epidermal muscle cell 

 is shown in Pig. 14. .Mallory's conn, tissue stain. X 875 



Fig. 16. — Description as for Figs. 14 and 15. But one set of constrictor 

 fibres shown; lumen of duct [l.d.) nearly closed. Mallory's 

 conn, tissue stain. 1650 



Fig. 17. — Longitudinal section of nearly empty poison gland. Secretion 

 (sec.) very small in amount, cell walls (c.u\) distinct, nuclei 

 clear and of irregular shapes. Semi-diagrammatic in unim- 

 portant details. Benda's iron haematoxylin. 342 



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