VI 



ADVEllTltiEMENT. 



The drawings were not only beautifnlly worked ui), but possessed the merit of 



extreme accuracy. 



In the use of the microscope, Chxrk showed not only mechanical skill and 

 ingenuity, but a patience, caution, and experience 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. He suggested improve- 

 ments, carried out by Spencer, at the instance of Professor Agassiz, in this instru- 

 ment. After leaving Cambridge he studied the Infusoria and lower plants, and 

 made drawings and notes, comprising descriptions of many new forms of Infusoria. 

 He planned an extensive work upon this subject, portions of which are now in 

 charge of the Boston Society of Natural History for publication. The drawings 

 are of great delicacy and beauty, and, had he lived to complete the work, it would 

 doubtless have been equal to if not in advance of Claparede and Lachman's famous 

 work on the Infusoria. He did not dissociate the Protophyta from the Protozoa, 

 regarding them as almost inseparable in nature; thus, as we have ascertained, in 

 liis lectures to his classes, well nigh anticipating Haeckel's classification of the 

 lowest forms of the animal and vegetable kingdom into the Protista and Protozoa. 



In June, 1860, he was appointed adjunct Professor of Zoology in the Lawrence 

 Scientific School, which he held until the expiration of his term of office; and, in 

 the spring and summer of 1861, gave a course of lectures on histology at the 

 Museum of Comparative Zoology. In the spring of 1864 he delivered a course of 

 twelve lectures at the Lowell Institute in Boston, which were published in the 

 same year, under the title of 'Mind in Nature; or, the Origin of Life, and the 

 Mode of Development of Animals.' This is, in all respects, for its usually sound 

 and clear thinking, its breadth of view, and the amount of original work it con- 

 tains, 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 European observers notable. 



In December, 1866, he was appointed Professor of Botany, Zoology, and Geology 

 in the Agricultural College of Pennsylvania. He resided at Centre County, Penn- 

 sylvania, the seat of the College, until April, 1869, when he was appointed to the 

 Chair of Natural History of the University of Kentucky. He lived at Lexington, 

 Kentucky, until February, 1872, when he was elected Professor of Veterinary 

 Science in the Massachusetts Agricultural College. 



During this period he suff-ered much from sickness ; still he managed in intervals 

 of college duties to produce some remarkable memoirs. lu his first paper on 



