42 SUMMARY OF CURRENT RESEARCHES RELATING TO 



or knobbed in form. The author finds that it is not only the testicular 

 cells that have the power of movement, but also the true seminal cells 

 within which the spermatozoa are developed. In the spermatozoa 

 the power of movement resides solely in the tail or flagellum ; the 

 power of free movement, of twisting and so on, is largely due to the 

 absence of any investment. One of the most ordinary forms of 

 spermatozoon is that with a nearly round head, in which the hemi- 

 sphere that carries the flagellum is darker than the other half (this is 

 in consequence of its being still covered by the nuclear membrane). 

 Flagella with quite rudimentary heads are by no means rare. 



Spermatogenesis.* — Dr. D. Biondi claims to have effected a 

 synthesis of the divergent observations which have been of late the 

 subject of so much discussion. The nature of his solution may be 

 best explained by his own summary. 



1. In all seminal canals, mature or immature, there is really only 

 one kind of cell (" Samenzellen," or round cells). 



2. The " epithelial cells " of Sertoli, the " Stiitzzellen " of Merkel 

 and Henle, the " spermatoblasts " of von Ebner are all secondary 

 modifications, arising from the protoplasmic remains of the round 

 cells after these have produced spermatozoa. 



3. All seminiferous cells (" Samenzellen ") arise from primitive 

 cells (" Stammzellen "), and lie in a semi-fluid albuminoid substance. 



4. In functional testes each primitive cell produces a generation 

 of cells which are arranged linearly in pillar-like fashion. 



5. In each pillar three zones are to be distinguished : (1) outer- 

 most, one cell, the primitive cell (" Stammzelle ") ; (2) two or three 

 mother-sperm-cells in a row ("Mutterzellen"); (3) four to six cells 

 in an innermost row^ (daughter-sperm-cells, " Tochterzellen "). 



6. When the generation is complete, differentiation into sperms 

 begins from the centre outwards. 



7. The three portions of the spermatozoon are formed wholly from 

 a' nucleus, the anterior half of which forms the head and the other 

 half the middle portion and tail. 



8. The spermatozoa do not move towards the periphery. 



9. After the complete modification of all the cells, each pillar 

 has the appearance of a bundle of spermatozoa. 



10. The expulsion of the sperms is effected by the expansion of 

 the cells of adjacent pillars. 



11. In the formation of sperms from the nuclei, there are remains 

 of the latter left unused, vfhich with the protoplasm form the semi- 

 fluid, albuminoid, intermediate or connective substance (" Zwischen- 

 substanz "). 



12. A bundle of sperms arising from a single pillar, imbedded in 

 the connective substance, and compacted by pressure, form a " sperma- 

 toblast " of von Ebner. 



13. As the pillar becomes modified into spermatozoa and con- 

 nective substance, and as the former are expelled, the foundation of 

 a new generation is laid by the division (tangential) of the primitive 

 cell (" Stammzelle ") of an adjacent pillar. 



* Arch. f. Mikr. Anat., xxv. (1885) pp. 594-620 (2 pis.)- See also this 

 Journal, v. (1885) p. 979. 



