284 NOTES. 



(38.) Fragments attributed to a cetaceous animal, another humble 

 form of the mammal class, have likewise been found in the great 

 oolite, near Oxford. 



(39.) De la Beche's Geological Eesearches, p. 344. 

 (40.) Lyell's Elements of Geology. 



(41.) The tertiary mammalia are chiefly described from the 

 beautiful work of Professor Owen, A History of British Fossil 

 Mammalia and Birds, 1845. 



(42.) Supplement to the Atomic Theory. 

 (43.) Carpenter on Life, Todd's Cyclopedia. 



(44.) From the Prize Essay of Dr. Carpenter (1838), under the 

 award of the professors of the Edinburgh University. 



(45.) Alison's Principles of Physiology, quoted in the above Prize 

 Essay. 



(46.) Treatise on the Forces which produce the organization of 

 Plants. New York, 1844. 



(47.) The absence of philosophic discrimination from the present 

 work has been illustrated by many critical references to this passage. 

 The simple fact is, that the reviewers have themselves failed in 

 discrimination ; not observing that it is the forms merely, not the 

 internal constitution, of living bodies, which I have suggested to be 

 a result of similar forces to those productive of the forms of crystals. 

 The idea, after all, did not originate here, but was adopted partly 

 from the following passage in Mr. Leithead's work on Electricity, 

 (1837) : 



" the form of the route of free electricity is modified by 



the medium through which it passes, and also by the electrical state 

 of such medium, or of that of the relative electrical conditions of 

 two bodies between which it is transmitted. If the medium through 

 which it passes possesses a very inferior conducting power, it is 

 obvious that a certain momentum must be requisite to enable the 

 fluid to force its passage to a given distance, and there will be a 

 point at which the momentum of the fluid and the resistance of the 

 body will exactly counterbalance each other ; but so soon as the 

 electricity has again accumulated to a sufficient degree to overcome 

 the resistance, it will again force its way in another direction, until 

 it arrives at another point of equilibrium. In this way we may 

 readily see the modus operandi of the electric fluid in imparting 

 regular forms to bodies ; and it is highly probable that its action in 

 this respect extends to the vegetable kingdom, and perhaps operates 



