578 r. A. E. CREW AND HONOR B. FELL 



development of fibrous tissue which in the case of the left-hand tubule 

 has entirely obliterated the lumen. The fibres in this case are very fine. 



Plate 21. 



Fig. 15. — Rabbit. Intertubular tissue, x 750. Shows a large number 

 of interstitial cells, one of which is in mitosis. The nuclei are large, circular, 

 and not very deeply staining. 



Fig. 16. — Rabbit. Intertubular tissue, x 750, Shows metamorphosed 

 interstitial cello. The nuclei arc of the same type as in fig. 15, but the 

 cytoplasm is much increased in quantity and is very granular. 



Fig. 17. — Rabbit. Epididymis, x 60, Almost normal in structure but 

 closely invested by adipose tissue. 



Fig, 18, — Rabbit. Semuiiferous tubule, x 380. A smgle large body 

 enveloped by degenerate epithelial cells is seen. The concentric structure 

 is most marked, A smgle primary ring is present surrounding a light 

 central area. Both the primary ring and the central area are marked by 

 secondary rings, 



Plate 22, 



Fig. 19. — Cat. Seminiferous tubules, x 350, The epithelial cells are 

 fairly normal, containing an oval nucleus with a well-marked nucleolus. 

 The centre of the lumen is occupied by a dark coagulated mass containing 

 degenerate nuclei. 



Fig. 20. — Cat. Semmiferous tubide, x600. The tubule shows little 

 sign of degeneration save absence of mitosis and the presence of a deeply- 

 stained ovoid body in the centre of the sjTicitial protoplasm. This probably 

 represents an early stage m the formation of bodies such as those found 

 in the goat and rabbit. 



Fig. 21. — Cat. Intertubular tissue, x 600, A few groups of interstitial 

 cells are seen, one of which is applied to the basement membrane of the 

 tubule on the right-hand side of the figure. The nuclei are darkly stained, 

 circular, and contain a nucleolus. The cytoplasm is much vacuolated. 

 Only a small quantity of iiitertubular tissue is present. 



Plate 23, 



Fig. 22. — Frog. Complete section of the displaced gonad. In the 

 peripheral tubules the structure is faii'ly normal but the tubules Ij'ing 

 more centrally are shrmiken and degenerate. Two ovum-like bodies are 

 seen in the lower half of the section. 



Fig, 23, — Frog, Ovum-like bodj- within semmiferous tubule, x 320. 

 The body consists of a dark outer layer formed by the coalesced heads of 

 the spermatozoa and a light granular central area composed of coagulated 

 semmal fluid and liquefied sperm flagella. 



