PENETRATOR • FREE-TRANSLATOR.COM • Definition of Penetrator

... spermatozoon copulates with one ovum; the membrane which is raised on the surface of the yelk immediately after one sperm-cell has penetrated (Figure 1.25 C) prevents any others from entering. All the rivals of the fortunate penetrator are excluded, and die without. But if the ovum passes into a morbid state, if it is made stiff by a lowering of its temperature or stupefied with narcotics (chloroform, morphia, nicotine, etc.), two or more spermatozoa may penetrate ...

— The Evolution of Man, V.1. • Ernst Haeckel