386 



PRACTICAL HISTOLOGY. 



[xxxv. 



spennatoblasts of the innermost layer. The latter, arranged in 

 groups, gradually elongate, and from them the groups of spermatozoa 

 are formed. Each group rests on and is connected with a susten- 

 tacular cell ; hence arose the old view that these sustentacular 

 cells produced the spermatozoa, and for this reason they were 

 formerly called spermatoblasts. The nucleus of a daughter-cell 

 forms the head and body of the spermatozoon, while the tail is 

 formed within the protoplasm, but it is connected with the nucleus, 

 and in its development grows out and forms a cilium. 



3. Isolated Cells from the Tubules. Macerate small frag- 

 ments of the testis in dilute alcohol 10-12 hours. Tease a small 

 fragment in glycerine. Observe the various forms of cells iso- 

 lated. 



4. Spermatozoa (H). Make a cut into the epididymis of a testis 

 removed from a rabbit as soon as possible after death. A milky 



F IG - 357. Tubules of Testis of Rat, showing Spermatogenesis. A. Less advanced stage: 

 B and C. More advanced stages. A and =T.S.; C=L.S. Memmiug's fluid and 

 safranin, x 300. 



juice exudes. Place a little of this on a slide and dilute it with 

 normal saline. 



(a.) The spermatozoa, each one with a head and a long vibratile 

 tail or cilium. By the side-to-side movement of the tail the whole 

 spermatozoon is moved onwards in a zigzag course. 



(b.) Add a drop of distilled water. The movements are arrested. 

 The spermatozoa are slowly killed. 



They may be readily preserved by smearing a little of the milky 

 juice from the epididymis upon a slide and allowing it to dry. It 

 is then covered and sealed. 



5. Spermatozoa of Newt and Frog (H). The testis of a newt 

 is teased in a mixture of alcohol and glycerine. 



(H) Observe the pointed head, body, and long tail of each sper- 

 matozoon. There is an intermediate part, which is best seen in a 

 stained preparation. From it springs a filament which appears to 

 be prolonged as a spiral filament around the cilium or tail. The 



