1873.] REPORT ON APPLES. 37 



Having thus outlined the argument, pro and coh., permit me to suggest 

 a reconciliation. In medio tutisswius ibis. Though the weight of argu- 

 ment and evidence as exhibited is all against the theory, there really is 

 some substantial truth in it after all. Ifo7i constat that a theory is un- 

 sound because its author's presentation of it begs the question or contains 

 an incomplete induction. 



1. There are two classes of trees. Of course no one would maintain 

 that any tropical tree or plant could endure freezing. But the trees and 

 shrubs of our latitude are all exogens or outside growers, and are of rad- 

 ically different structure from the endogens or inside growers of the tro- 

 pics. The humble representatives of the latter class in our Northern 

 climes are all annual plants, which perish with the first freezing of Au- 

 tumn. Among the important distinction* between these two great classes, 

 to represent which we may take our Apple tree and the Palm as proper 

 typical forms, there is this, which, though well known, is usually little 

 noticed in elementary works: That while the inside-growing palm wholly 

 consists of living vegetable matter, the only living parts of the outside- 

 growing apple tree are the extremities, (that is, the buds and foliage and 

 the tips of the roots and rootlets,) and the newest strata of wood and bark 

 and especially the interposed cambium layer, which, annually renewed, 

 maintains a living communication between the extremities. The apple 

 tree, like all other plants of this highest form of vegetable life, is a com- 

 posite being or community — not an individual in the same sense that a 

 man, horse or bird is an individual, but an aggregation of many units. 

 The true unit or individual is the bud. The exogenous tree resembles a 

 coral reef or community of compound animals of the lowest class where 

 the structure is built up by successive generations of avast number of in- 

 dividuals. Only the extremities and surface are alive, and all underneath 

 are the lifeless I'emains of preceding generations. In the tree, as in the 

 coral reef or polypidom, there is no portion now alive that was alive a 

 few years ago. Life proceeds constantly outward from older to newer 

 parts, and death follows imri passu. The foliage perishes annually, the 

 internodes or joints that bore them, enclosed under the wood of succeed- 

 ing generations, are transferred into lifeless heart-wood, and the bark that 

 once covered them falls off. The lowest grade of animals, the radiata of 

 which the star fish is the type, and to which the polyps or coral animals 

 belong, truly embraces the whole vegetable kingdom. All plants " have 

 organs arranged in a radiate manner around a central axis." 

 . Thus we see that only a small portion of the exogens or outside-grow. 

 ing tree is really alive, and that life only inheres in its outside growth. 

 The distinction between the duramen or heart-wood and the albumen or 

 sap-wood is as well known to common observers as it is to botanists. The 



