AND THE LOWER ANIMALS. 183 



pointed out in their splendid treatise, that strange 

 blunders and mistakes have been made by some of 

 those whose views more or less resembled those of 

 Ehrenberg. However, my own personal observations 

 have always compelled me to admit the existence 

 of reproductive bodies, which play the part of eggs, 

 and whose minuteness alone prevented my perceiving 

 very distinctly the three constituent parts.* At 

 present there is no room for doubt either on this point 

 or on the others. In those beings, which, as regards 

 size, approach the lowest bounds of organic develop- 

 ment, modern science has, after much hesitation, de- 

 finitively proved the existence of all the essential 

 phenomena of normal reproduction. The Infusoria, 

 like Mammalia, Birds, Mollusks, and all other animals, 

 deposit ova which are characterized by the presence 

 of three concentric spheres. As in all other species, 

 these ova cannot be fertile till they have been 

 influenced by the male element, but, when this has 

 operated, the germinal vesicle and spot disappear, 

 prior to the conversion of the yelk into a new being. 



These facts were at once the most important 

 in a scientific aspect, and the most difficult to 

 prove. Perhaps one of the greatest benefits which 

 has been conferred on general physiology, is that 

 which has been rendered by a young French naturalist, 

 M. Balbiani, who has placed these facts beyond 

 all discussion, and caused them to be accepted by 

 those who appeared least likely to admit the existence 

 of normal reproduction among infusoria, f 



* " Eevue des Deux Mondes," 1856. 



f Before M. Balbiani's publication, there had been but one or 

 two very incomplete treatises on this difficult subject. One was 



