856 SPARKS FROM A GEOLOGIST'S HAMMER. 



" gothic " ; as the zoologist says the stjde of a large por- 

 tion of the animal kincjdom is " vertebrate." But our 

 stranger has never seen an edifice in process of construc- 

 tion, and he conjectures the method in accordance with 

 which its features might have been originated and com- 

 bined. Evidently, he says to himself, one method would 

 be the full completion of each portion of the building 

 before beginning another portion, as a mud-wasp builds 

 its cell. At length, however, he discovers an edifice in 

 process of erection ; as the biologist studies the building 

 up of an animal from the egg. An excavation is first 

 made for the foundations; this is the "primitive furrow." 

 The basement walls are raised around it; the sills and 

 the floor-timbers are laid ; these are the " protovertebrae." 

 Next the side walls are raised and the roof is closed in. 

 This is the median junction of the body walls in the em- 

 bryo. Thus the most general features of the structure 

 first appear. The places of partitions and stairways are 

 indicated by rough timbers, and the plan of the house is 

 outlined. As the work proceeds the rough timbers are 

 covered with flooring and lath ; then the walls receive 

 coats of brown mortar, and, lastly, a white finish. Still 

 remain the casings and mouldings, and paint and varnish. 

 Now the house is complete, and our gratified stranger 

 concludes that the stately edifice, the cathedral, the town 

 hall, were all constructed according to a method of " evo- 

 lution," the most fundamental parts first, the details 

 successively filled in. He has discovered the method, the 

 order of succession of the parts. Now he knows that all 

 buildings are constructed according to a law of evolution; 

 as the biologist has learned in reference to animals, and 

 the cosmologist in reference to worlds. But our stranger 



