GENERAL CATALOGUE. 105 



theory of the cell, on the structure of the protozoa and the 'nature 

 of protoplasm. In the use of the microscope he showed not only 

 mechanical skill and ingenuity, but a patience, caution, and expe- 

 rience in difficult points in histology, which undoubtedly placed 

 him at the head of observers in this country, and rendered him, 

 perhaps, inferior to few in Europe. He used the highest powers 

 with a skill that few if any living observers have surpassed. His 

 worfc entitled ' Mind in Nature ' is, in all respects, for its usually 

 sound and clear thinking, its breadth of view, and the amount of 

 original work it contains, perhaps the most remarkable general 

 zoological work as yet produced in this country. If the author 

 had left us no other work, this alone would testify to years of the 

 severest labor and independent thought. It anticipated certain 

 points in histology, and the structure of the Protozoa and sponges 

 especially, which have made the succeeding labors of some Euro- 

 pean observers notable." Dr. A. S. Packard. Jr., in a Memoir 

 read before the National Academy of Sciences, in 1874, speaks of 

 Mr. Clark as follows: k - Within the year past we have lost a 

 member who may be said, without disparagement to others labor- 

 ino- in the same field, to have been the foremost American histolo- 



O 



gist and microscopist, and one of our most skilful and accom- 

 plished biologists ; one the rule of whose scientific life was a 

 practical application of experimental philosophy. A true natu- 

 ralist, he was an enthusiast, and yet in his methods of study 

 severe, exact, and in all respects scholarly." 



A list of the scientific writings of Henry James Clark is here 

 subjoined. 



The Peculiar Growth of Rings in the Trunk of Rhus toxicoden- 

 dron. (Proc. Amer. Acad., Vol. III., 1856, p. 335.) 



The Excentricity of the Pith in Ampelopsis quinquefolia and 

 Celastrus scandens. (unpublished.) 



Contributions to the Natural History of the United States. 

 1857-62. (Conjointly with Prof. Louis Agassiz.) 



Recapitulation of the " Embryology of the Turtle," as given in 

 Professor Agassiz's " Contributions to the Natural History of the 

 United States." (Am. Jour, of Science, II. Vol. XXV., 1858, 

 pp. 342-357.) 



Some remarks upon the use of the microscope, as recently 

 improved, in the investigation of the minute organization of 

 living bodies. (Proc. Amer. Acad., Vol. IV., 1859, pp. 136- 



