THE GENITAL ORGANS OF THE MALE. 



flattened, or lancet-shaped head, and a filiform tail terminating in a point ; this 

 tail is often furnished at its origin with an enlargement, or unilateral or bilateral 

 alae. Their form is slightly modified during their course through the excretory 

 ducts. (In the different species, though possessing certain fixed characters, the 

 spermatozoa yet offer some curious diversities. Some of these are well exhibited 

 in the annexed representations of 



these particles, found in the semen Fig. 521. 



of very dissimilar animals.) 



The spermatozoa move by undu- 

 lations of the tail (Grohe attributes 

 the motion to the contractile pro- 

 toplasm contained in the head) ; 

 ihey can traverse '004 m. in a 

 minute. Their movements persist 

 for several days in the genital 

 organs of the female ; they are 

 suddenly arrested by water, acids, 

 and the electric spark ; on the 

 contrary, they are animated by 

 alkaline fluids. (The movements 

 cease when the spermatozoa are ex- 

 posed to a temperature of 120° 

 Fahrenheit.) These bodies are de- 

 veloped in the cells of the tubuli 

 seminiferi by a modification of 

 their contents. Their development has been already described above. 



1, Spermatozoon of the fro^ ; 2, of the triton ; 3, of 

 the finch ; 4, of the field-mouse ; 5, of the hedge- 

 hog ; 6, sheep, a, Head with nucleus ; b, body ; e, 

 tail. 



Excretory Apparatus of the Semen. 



1. The Epididymis and Deferent Canal (Figs. 368, 517, 518, 519). 



Epididymis. — The organ thus named commences the excretory canal of the 

 testicle. It is a body elongated from before to behind, placed against the upper 

 border, and a little to the outside, of the testicle. It has a middle portion and 

 two extremities. 



The middle is contracted, flat on both sides, and free outwardly ; it is related, 

 inwardly, to the spermatic vessels and the testicle, to which it is attached by a 

 very short serous layer. The extremities are expanded, and adhere closely to the 

 testicle. The anterior — the largest — is named the head of the epididymis, or globus 

 major. The posterior, the tail of the epididymis, or globus minor, is more detached 

 from the testicle, and is curved upwards to be continued by the deferent canal 

 {vas deferens). 



Structure. — The epididymis results from the union of from twelve to twenty 

 small tubes — the efferent ducts — which, arising from the rete testis, open together, 

 at a variable distance, into the globus major. Towards the globus minor there 

 is only one duct, which is more voluminous and less flexuous, and ends by becom- 

 ing detached from the posterior lobe of the epididymis to constitute the vas 

 deferens. 



The organization of the walls of these ducts is not the same throughout. 

 Thus, in the efferent ducts it comprises a simple ciliated epithelium, resting on a 

 proper amorphous membrane, which again is placed on unstriped circular fibre, 



