18 HUMAN SPERMATOGENESIS: A STUDY OF INHERITANCE. 



to exhibit graded variations in a regular curve, the mean being from 15 to 15.9 

 mm., and 86 per cent, falling between 13 and 18.9 mm. Therefore, although 

 there is a remarkable range of volume, it is continuous variation around the 

 mean, and the spermatozoa cannot be arranged into two or more size classes. 



B. DISCUSSION. 



Of the numerous accounts of mature human spermatozoa since their first 

 description by Leeuwenhoek (1677), may be specially mentioned those of Jensen 

 (1887), Broman (1902), Ballowitz (1891), Retzius (1902, 1909, 1910), and the 

 diagrammatic figures given by Meves in the work by Waldeyer (1906). Bro- 

 man's descriptions treat to great extent abnormal spermatozoa, a subject upon 

 which we shall not enter, and he described a spiral thread around the middle 

 piece; that the mitochondrial substance composes a spiral thread has been 

 strongly denied by Retzius. Prenant (1888) also found a spiral thread, and 

 believed it terminates posteriorly in a distal centriole ("bouton inter caudal ") . 

 Meves' figures show a somewhat greater complication in the region of the middle 

 piece than I have been able to determine. By the use of isotonic solutions 

 Koltzoff (1908) found the entire sperm enveloped by a semipermeable membrane, 

 a structure not seen by other writers. Retzius (1909) found the most anterior 

 centrosome (our anterior portion of the proximal centrosome) to consist quite 

 regularly of two granules. 



The idea I have formed of the structure of the human spermatozoon in its 

 mature condition is represented in the diagrammatic figure 16, PI. IV. Applying 

 the new terminology of Waldeyer it is seen to be composed of the following main 

 parts: the caput or head {Cp.) 9 the collum or neck {CI), and the cauda or 

 tail {Cd.). The head consists of a pars anterior (P. A.) which alone contains a 

 few droplets of karyolymph (these quite variable in number and size), and of a 

 pars posterior (P.p.) ; only occasionally does a groove demarcate the two. The 

 neck consists of an anterior nodulus (Nd.A.), the anterior portion of the proximal 

 centriole; a posterior nodulus (Nd.P.), the posterior portion of the proximal cen- 

 triole; and of a structureless, non-staining intermediate mass (M.Int). The 

 tail is composed of a junction piece (pars conjunctionis, P.C.), a pars principalis 

 (A v\ * wtenuDBL filament (pars terminalis, P.T.); the axial thread 



i£S ii th T gh ° Ut the taiL Within th * Action P^ce lie the mito 



alnhl? n p !' ^ ? aking a mantle and not a BPiwl thread around the 

 axial thready Cytoplasm (Cyt.) seems to be limited to the junction piece. 



series f^°TT^ V ^ but little has been d <™. Bardeleben in a 

 kZn[ s ^^ 7 h - i h ° Se ° f 1897 and 1898 are the ™s* important, made 

 EoZer hrnotfdT/S Strated ** the most * art * ™clear small figures. 



n-omTt of a iT'i v ^ "J** Shrinka * e of the n ™leus, *** the e i ection 

 he d ops i^ but believed this to furnish 



SSiSl. ^TS 1, u He als ° described th * euff, the division of the 

 proximal centriole, and held the mitochondrial sheath to be formed from the 



