242 11AMBLES OF A NATURALIST. 



More precise information and more exact methods 

 have, however, overthrown these hypotheses. After 

 having for a long time attempted to supply the defi- 

 ciencies of science by mere creations of fancy, and 

 after having endeavoured to explain that which did 

 not admit of explanation, embryologists have turned 

 in our own day to rigid experiment and observation. 



Under the guidance of these, we learn that in the 

 two kingdoms of nature, epigenesis, or successive 

 formation, is the great law, which presides not only 

 over the development, but over the very organisation of 

 germs. Buds, bulbils, eggs, or seeds, in short all re- 

 productive bodies, are produced from a pre-existing 

 individual being, which elaborates them from its own 

 substance, under the influence of vitality, and in con- 

 sequence of phenomena of nutrition and secretion 

 similar to those from whence result all the other 

 products of the organism. At first imperfect, these 

 germs are successively completed, and only become 

 capable of fulfilling their important functions after 

 they have attained to maturity. Some, as we have 

 already remarked, possess in themselves all the vital 

 activity that is necessary for their development, in 

 which case, properly speaking, there is neither father 

 nor mother ; others, on the contrary, require the in- 

 tervention of a special agent, and here first appear 

 distinct sexes which concur in the reproduction of 

 their species. 



In the plant as in the animal, the female secretes 

 a germ that must be fertilised, while the male pro- 

 duces the fertilising agent. From the contact of 

 these two elements there results a new individual. 



