DEVELOPMENT OF THE SPERMATOZOA. 155 



stance of the spermatozoa is developed independently from the 

 cell contents, having the same relation to it, therefore, as the 

 sarcous elements have to the muscle cells. 



According to the researches of Schweigger-Seidel, the sper- 

 matozoa are by no means simple nuclear structures, but con- 

 stitute single-ciliated cells, proceeding from the metamorphosis 

 of an entire cell. 



In my first communication that appeared simultaneously 

 with his,* I expressed myself to the effect that not only the 

 nuclei but the protoplasm of the seminal cells took part in the 

 formation of the spermatozoa, and I endeavoured to furnish a 

 description of their development in Mammals, Birds, and 

 Amphibia. In a second communication I added my obser- 

 vations on Arthropoda and Mollusks. 



In accordance with the observations of Zenker f on Asellus, 

 and with those of KefersteinJ: on Helix pomatia, I have observed 

 the development of the spermatozoa occur with persistence of 

 the original nucleus. 



Since this date Kolliker has again expressed his views 

 upon the development of the spermatozoa, but finds no reason 

 to differ from his later statements. 



Owsjannikow || supplies us with very interesting data upon 

 the still little examined development of the spermatozoa in 

 Fish. The testes of the Salmonidce possess epithelial cells, 

 that are usually cylindrical, and arranged in two layers. The 

 cells present a large white nucleus, with distinct nucleoli and 

 protoplasm. The cells of the second and third layers exhibit 

 fission of the nucleus and protoplasm, undergo coincident 

 increase in size, and may ultimately contain from ten to fifteen 

 or more young daughter-cells, without losing their form. These 

 constitute the young 'spermatozoa. The nucleus of the cells 

 becomes the head, and the protoplasm surrounding it the 

 tail. 



* Max Schultze's Archiv, Band i., p. 403. 



t Archiv fur N., pp. 20 and 103. 



Die Classen und Ordnungen des Thierreiches, Band iii., p. 1215. 



Handbuch der Gewebelehre, p. 530. 



|| Bulletin de V Academic de St. Petersbourg, T. xiii., p. 245. 



