264 MR. NEWPORT ON THE IMPREGNATION OF THE OVUM IN THE AMPHIBIA 



of a mere vehicle for the ready transmission of the spermatozoon to the ova, and as 

 allowing greater freedom of motion to these bodies. 



It is true, as WAGNER and LEUCKARDT have stated, that but little motion can be 

 observed in the spermatozoa of Insects when they are united into cords ; yet this 

 seems to be due rather to their union into these masses, and to have reference to 

 their mode of ejection from the body of the male, as in the Triton, and is known to 

 take place during their collection in the deferential vessels, than to any real absence 

 of a power of motion in them. This is not their condition when brought into contact 

 with the egg at the time of impregnation. When the fluid of the male insect, during 

 pairing, is passed into the sperrnatheca of the female, where it may be destined to 

 remain for an indefinite time, the spermatozoa compose the chief portion of it, as in 

 the Tritons; but, during their residence in the spermatheca, the spermatozoa are 

 mixed with a fluid, which is supplied by a gland attached to that organ, and which 

 becomes to them a vehicle like the liquor seminis, and allows of their separation and 

 independent motion, and thus appears to answer the purpose of the true liquor 

 seminis in the Mammalia. At the period when the ova are descending from the 

 ovaries, the movements of the spermatozoa become more distinct ; and when these 

 bodies are brought into contact with the egg, as it passes the outlet of the sperma- 

 theca, they become more isolated, and their movements more intense, as I have seen 

 in the case of the Orthoptera. From these circumstances I am led to believe that 

 some degree of motion will ultimately be observed to mark the perfect condition ot 

 the impregnating agent in all animals. The facts already mentioned coincide with 

 this view, and point to the probability that the degree of impregnating force in each 

 individual may perhaps be indicated relatively by the degree or intensity of motion 

 in the spermatozoon, and the duration of this force by the length of time which the 

 spermatozoon continues in motion. 



The established fact, that a difference in the structural conformation of a body is 

 the invariable result of a difference in the relations, proportions, and composition of 

 its material constituents, has always afforded reason for presuming that some material 

 influence may be transferred from the substance of the spermatozoon to the contents 

 of the ovum, at the time of impregnation. The function of impregnation appears to 

 be one of definite relations and proportions. Thus we have seen, when only a few 

 spermatozoa were applied to the ovum on the point of a pin, that full impregnation 

 was but rarely effected. In most instances of such limited application, the yelk 

 underwent only partial segmentation, and its changes were then gradually arrested, 

 and no embryo was produced. If, however, the pin point which had been charged 

 with spermatozoa, instead of being applied to the ovum for an instant only, was 

 allowed to remain in contact with the egg for a second or two, and thus by capillary 

 attraction became drained of the spermatozoa which adhered to it, and, as a conse- 

 quence, thus made to deposit a greater number of these bodies, which were not 

 afterwards attempted to be removed or destroyed, then impregnation was sometimes 



