THE OVARIAN EGG. 281. 



eggs, or produced by natural division, or by 

 budding ; and that the constancy of these normal 

 processes of reproduction, as well as the uni- 

 formity of their results, precludes the idea that 

 the specific differences among animals have been 

 produced by the very means that secure their 

 permanence of type. The statement itself im- 

 plies a contradiction, for it assumes that the same 

 influences prevent and produce changes in the 

 condition of the Animal Kingdom. Facts are all 

 against such an assumption ; there is not a fact 

 known to science tending to show that any being, 

 in the natural process of reproduction and multi- 

 plication, has ever diverged from the course nat- 

 ural to its kind, or that a single kind has ever 

 been transformed into any other. But this once 

 established, and setting aside the idea that Em- 

 bryology is to explain to us the origin as well 

 as the maintenance of life, it yet has most im- 

 portant lessons for us, and the field it covers 

 is constantly enlarging as the study is pursued. 

 The first and most important result of the 

 science of Embryology was one for which the 

 scientific world was wholly unprepared. Down 

 to our own century, nothing could have been 

 farther from the conception of anatomists and 

 physiologists than the fact, now generally admit- 

 ted, that all animals, without exception, arise 

 from eggs. Though Linnaeus had already ex- 



