MATERIAL AND METHODS. II 



At this point it is convenient to define two terms which will be fre- 

 quently used in the following pages, viz, "insemination" and "semina- 

 tion." The first refers only to the introduction of the male sexual 

 elements into the genital tracts of the female by the act of coitus or 

 otherwise. The second, which means the same in this connection as the 

 German "Besamung," applies to the access of the spermatozoa to the 

 eggs in the oviduct, the coming into contact of the male and female 

 reproductive cells. Both terms are distinct from "penetration" and 

 "fertilization." 



.-SP 



p IG- p m Glass syringe and speculum, about three-fourths actual size. 



In order to control the time of semination, artificial insemination 

 has been used in nearly all the cases where fertilized eggs have been 

 desired. The method is a simple one, and with a little experience the 

 operation becomes easy. It may be performed quickly and without 

 the use of ether, and apparently produces neither pain nor injury to 

 the mouse. The spermatozoa are obtained from the vasa deferentia of 

 a male killed for the purpose and are put into a small amount of tepid 

 physiological salt solution (0.75 per cent ordinary table salt), in which 

 they will live for several hours. The spermatozoa from one male are suffi- 

 cient for several females. The mass of spermatozoa thus diluted is 

 drawn into the long, narrow part of a glass syringe (S, fig. F), made 

 for this purpose. If the spermatozoa become disseminated in the salt 

 solution a fact easily recognized in the syringe because of the increas- 

 ingly milky appearance of its contents and a diminution of the solid 

 mass of spermatozoa they are active and capable of fertilizing. In 

 practicing artificial insemination, the mouse is held under the left hand, 

 being confined between two pieces of cotton-batting, one above and one 

 below. The base of the tail is grasped between the first joint of the left 

 thumb and the metacarpal of the left forefinger. 



By means of a glass speculum (SP, fig. F) introduced into the vagina 

 and held between the left thumb and the tip of the left forefinger, it is easy 

 to see the somewhat constricted orifice of the neck of the uterus, and to 

 introduce into the uterus by means of the syringe operated by the right 

 hand a very few drops of the fluid containing spermatozoa. The specu- 

 lum and syringe are best kept at body temperature by immersing them 

 in hot water, taking care not to injure the spermatozoa. Only sperma- 

 tozoa from freshly killed males were used. 



There can be no doubt that the eggs fertilized by means of artificial 

 insemination are perfectly normal. Artificial insemination is a common 

 practice in the breeding of horses and dogs, the offspring produced by 

 such methods being quite sound and perfect (Heape, 1897; Iwanoff, 



