THE MICROCOSM OF THE EGG 139 



said, as the weaver at the loom, the paternal and 

 maternal contributions being the warp and woof 

 of the future web. (4) When the sperm-cell enters, 

 a wave of contraction, starting from the upper pole, 

 passes through the ovum, and a small quantitiy of 

 fluid is expelled which insinuates itself between the 

 surface of the egg and the innermost layer of the 

 egg-membranes. (5) Finally, the sperm-cell sets up 

 awakening changes in the living substance of the 

 egg, which then passes from static to dynamic 

 equilibrium. The formative materials are redis- 

 tributed and stabilized in a direction determined by 

 the meridian of the sperm's entrance. This new 

 architecture is respected in the subsequent cleavage 

 of the developing egg. Another effect is that the 

 living substance of the ovum becomes suddenly 

 refractory to the entrance of another sperm-cell, 

 which would be apt to induce monstrosity. This 

 "blocking" of the egg-cell is sometimes accom- 

 plished by the contraction, already referred to, 

 which shuts a little gateway (micropyle) present in 

 the egg-envelope of many ova. 



One of the most interesting chapters in modern 

 biology concerns artificial parthenogenesis, i.e. 

 experimental ways of launching an unfertilized egg 

 on the voyage of development. Most bee-experts 

 believe that unfertilized eggs laid by the queen 

 develop into drones, who, therefore, have a mother 

 but no father. This is natural parthenogenesis, 

 and there are many other instances. But it is now 

 known that in a variety of cases, from sea-urchin to 



