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The nucleated cell ! that minute organic structure which the 

 unaided eye cannot discern, yet constituting the first stage of 

 every living being, the seat of so many of the complex pheno- 

 mena of animal and organic life, and the agent by which even 

 the mind itself retains its grasp and exerts its influence upon the 

 living structures with which it is associated. In entering upon so 

 difficult a subject as this, it was not expected, nor is there any 

 reason to suppose that he himself expected, that he should not lay 

 himself open to criticism. The ablest living histologist, KoUiker, 

 in speaking of the subject of the development of tissue, uses 

 the following language : " Not only does histology not possess a 

 single law, but the materials at hand from which such could be 

 deduced are as yet relatively so scanty, that not even any consi- 

 derable number of general propositions appear well founded." 

 As laws and general propositions were among the especial objects 

 of Dr. Burnett's researches, it will be seen at once that he has 

 entered boldly into a contested field. But it is to follow him in 

 his labors, and not to hold up to criticism his results, that we have 

 at present to do. 



His subject is discussed under the following heads : 



1st. Cell-genesis, under which he treats of the origin of cells, 

 and advocates a peculiar mode of development, which he claims 

 as original with himself, and the result of his own observations. 



2d. Cell physiology, or healthy function. 



3d. Cell pathology, or diseased function. 



4th. Cell philosophy , or 1st, the relations of cells to the teleo- 

 logical view of organization ; 2d, the direct agency of cells in 

 the production and manifestation of nervous power, the intellect- 

 ual processes, &c. 



The general results of his studies of cell life and cell genesis 

 are in his own words as follows : '^ The great outstanding fact 

 which appears before us as the result of these studies is, that 

 there is fundamental unity of organization. This we have seen 

 to consist in elementary particles, which in both animals and 

 plants are formed upon a common plan. It was the opinion of 

 Schwann and Schleiden, who truly originated this view, that this 

 plan consisted in the precixislence of a solid fundamental body, 

 (the nucleus) around which is formed a membrane ultimately 



