150 THE TESTES, BY V. LA VALETTE ST. GEOEGE. 



three band-like rows of roundish bodies, an anterior, a middle 

 and a posterior. Hartnack regards these bands as elevations 

 and depressions that reveal themselves to the eye of the 

 observer, according to the direction of the incident light, by a 

 play of light and shade. Valentin and Fleury depict these bands 

 in the Bear, Rabbit and Dog. The Cat, Ram, and Guinea-pig also 

 exhibit them, though with progressively less and less distinct- 

 ness. They are seen without much difficulty with moderately 

 powerful lenses, and I have detected them in the Dog and 

 Rabbit with a No. 9 Hartnack * They constitute good test 

 objects for the microscope. 



Grohe,f as the result of his careful inquiries, considers the 

 spermatozoa to consist of two parts, a structureless investment 

 and contractile contents, the latter being chiefly collected in 

 the head. He regards the above-mentioned bands as due to a 

 peculiar distribution of the contents of the body. 



Schweigger-SeidelJ so far agrees with him that he admits 

 the existence of an external limiting membrane and contents, 

 though he has only been able to perceive the former as a 

 separate membrane in Amphibia and Birds. 



Fig. 182. 



Fig. 182. Spermatozoa of the Bat, with distinct intermediate 

 portion. 



Schwetgger-Seidel distinguishes an " intermediate segment" 

 situated between the head and tail, and demonstrates its exist- 

 ence in the Frog, Triton, Cock, Finch, and many Mammals. I 



* Ueber die Genese der SamenJcorper, " On the Development of the 

 Spermatozoa." Max Schultze's Archiv, 1867, Band iii., Taf. xiv., Fig. 2 

 and 5. 



f Yirchow's Archiv, Band xxxii., p. 416. 



J Schultze's Archiv, Band i., p. 309. 



