53 



appear in each jaw, but that the further progress of these could not 

 be observed, none of the specimens the author has had opportunities 

 of inspecting, appearing to be more than seven years old. 



Mr. Home proceeds next to observe, that the elephant, the Sus 

 aethiopicus, and the wild boar, are the only recent animals in which 

 he has hitherto met with so extensive a masticating surface of the 

 grinding teeth ; the human species only excepted, in which the mode 

 of dentition is somewhat upon the same principle as that of the wild 

 boar, with this difference, that the hindmost teeth, called, from the 

 late period of life at which they cut the gum, Dentes Sapientiae, do 

 not exceed the others in size, and have often not sufficient room in 

 the jaw to come into their regular place. A conjecture is hence de- 

 rived, that when the period of man's life was longer than it is at 

 present, the growth of the posterior part of the jaw was continued 

 for a greater length of time, so as not only to make room for the 

 present, but perhaps also to admit of a succession of a still greater 

 number of additional grinders. 



Upon comparing the grinders of the boar with the large fossil 

 teeth found on the banks of the Ohio, they were found so much alike, 

 both in their external appearance and internal structure, as to render 

 it more than probable that they are teeth of the same kind, only dif- 

 fering in size. Not so, however, those of the fossil skeleton some 

 time since found in South America, and described by M. Cuvier. 

 These were found so unlike those of the boar, or the above-men- 

 tioned incognitum, as to leave no doubt of its being an animal of a 

 different genus. 



From the progressive mode of dentition above described, it is in- 

 ferred, that the animals to which it appears to be peculiar, have by 

 nature been intended for great longevity. This we know to be the 

 case in the elephant : and though opportunities have not yet offered 

 for ascertaining the term of life of the wild boar, some quotations 

 from ancient authors are here adduced, which indicate that boars of 

 enormous size have at different times existed ; whence the proba- 

 bility is inferred that their bulk must have been the growth of many 

 years. 



Account of some Experiments on the Ascent of the Sap in Trees. In a 

 Letter from Thomas Andrew Knight, Esq. to the Right Hon. Sir 

 Joseph Banks, Bart. K.B. P.R.S. Read May 14, 1801. [Phil. 

 Trans. 1801, />. 333.] 



The author prefaces his paper by declaring that the cause of the 

 ascent of the sap in trees appearing to him not to have been as yet 

 satisfactorily accounted for, he resolved to enter on an experimental 

 inquiry on the subject ; and that having met with some facts of which 

 he had found no mention in any author, he flattered himself an account 

 of them might not be unacceptable to the Society. 



The first experiments were made with a view to determine whether 

 the sap does actually, as has been thought by some, ascend along 



