152 THE TESTES, BY V. LA VALETTE ST. GEORGE. 



ment. The duration of the movement varies considerably with 

 the medium in which they are placed. In the body of the 

 animal they last as long as forty-eight hours, but in the female 

 generative organs they may be perceived even after eight 

 days have elapsed. 



Alkaline solutions act favourably in maintaining the move- 

 ment, whilst acids, or the addition of a large quantity of water, 

 act prejudicially. Concentrated solutions of certain salts, of 

 sugar, and albumen, according to the discovery of Kolliker,* are 

 capable of re-exciting movements in spermatozoa that have 

 been rendered quiescent by the addition of water. Solutions 

 of caustic potash and soda, containing from 1-32 to 50 per 

 cent., are excitants ; and woorara is a powerful irritant. 

 Cocain (? codein), like sulphate of morphia, exhibits no action 

 on the movements (Wagner, Kolliker, Leuckart, Mantegazza). 

 According to the last-named author,f the spermatozoa preserve 

 their power of movement at temperatures varying from 15 

 C. to + 47 C. (= 5 to 116 Fahr.) 



Frozen spermatozoa recommence to move on being thawed. 

 They may be kept at a temperature of C. (32 Fahr.) for 

 four days without losing their motor power. 



According to Kolliker, semen dried after being placed in 

 indifferent fluids and certain saline solutions will sometimes 

 exhibit movements in the contained spermatozoa when moist- 

 ened with the same fluid or with water. 



DEVELOPMENT OF THE SPERMATOZOA. The origin of the 

 spermatozoa has been so frequently investigated, that it is 

 remarkable this subject has not long since been exhausted. 

 There are, however, special difficulties in the way, dependent 

 on the minuteness of the objects under examination, the 

 discovery of completely indifferent fluids, and the circumstance 

 that in the higher animals, at least, the various forms pre- 

 sented by the spermatozoa at different stages of development, 

 are not very well defined. Before we enter into a considera- 

 tion of their origin, it is right that we should examine the 



* Zeitschrift filr wAssenschaftliche Zoologie, Band vii. p. 201. 

 t Journal de V Anatomic et de la Physiologic, 1868, p. 184. 



