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AN AMERICAN TEXT- BOOK OF PHYSIOLOGY. 



The middle-piece (m) is a short, cytoplasmic rod, probably containing a cen- 

 trosome. The tail (/) is a delicate filiform, apparently cytoplasmic structure. 

 and analogous to a single ciliuni of a ciliated cell. The tail is tipped by an 

 excessively fine, short filament, the end-piect (e). The most 

 . abundant of the .-olid chemical constituents of the spermato- 



zoon is nuclein. probably in the form of nucleic acid, which 

 is found in the head. Other constituents are proteids, prota- 

 mine, lecithin, cholesterin, and fat. 



The structure and power of movement of the spermatozoon 

 plainly show it to be adapted to activity. It is not burdened 

 by the presence of food-substance within its protoplasm. It 

 is the active clement in fertilization ; it seeks the ovum, and 

 it i- modified from the form of the typical cell for the special 

 purpose of fertilization. The nucleus is the fertilizing agent. 

 The head is plainly fitted for facilitating entrance into the 

 ovum. The tail is a locomotor organ capable of spontaneous 

 movements, and, after expulsion of the semen, it propels the 

 cell, head forward, through the liquid in which it lies. The 

 movement is a complex one, and is effected by the lashing 

 of the tail from side to side, accompanied by a rotary move- 

 ment about the longitudinal axis. The rate of movement has 

 fig. 218.— HamaD been variously estimated at from 1.2 to 3.6 millimeters in the 

 spermatozoa (after m i nute . Spermatozoa taken directly from the testis are 



Retziust : .1, seeD en . •' 



/ace; h, head!; m, quiescent ; normally they begin to move when mixed with 



renSpTece 65 jT^ the secre1 ions of the access01 7 sexual organs. 1 Toward heat, 

 seen from the si.ie. cold, and chemical agents spermatozoa behave like ciliated 

 cell-. 



Ripe spermatozoa appear to be capable of living for months within the male 

 genital passages, where they are probably quiescent. Outside of the body 

 they have been kept alive and in motion for forty-eight hours. Tt is not 

 certain how long they may remain alive within the genital passages of the 

 human female. Diihrssen- claims to have found motile spermatozoa in the 

 oviduct at leasl three and one half weeks after coition. It seems not improb- 

 able that within the female organs their environment is favorable to a some- 

 what prolonged existence. In this connection it is of interesl to know that 

 spermatozoa capable of fertilizing have been known to live within the recep- 

 taculum ■•« minis of a queen bee for three years. 



Spermatozoa are produced in large numbers. Upon the basis of observa- 

 tions in several individuals. Lode 3 computes the average production per week 

 as 226,257,000, and in the period of thirty years from twenty-five to fifty- 

 five years of age the total production as 339,385,500,000. This excessive 

 production is an adaptation by nature thai serves a a compensation for the 



l Cf. Walker: Archivfur AnatomU und Physiologic, Anatomischer Abtheilung, 1899, S. 313. 

 2 Diihrssen: CmtraJblatt fur Gynakologie, 1893, xvii. S. 592. 

 'A. Lode: Pjiiiger's Archivfur die gesammte Physvdogie, 1891, 1. 



