NATURAL HISTORY OF THE DIATOMACEjE. 417 



plishment of their labors. To properly comprehend the structure and 



modes of formation of strata, be they made up of solid rock or more 



loosely aggregated material, he must be a mathematician of no low order. 



To understand the how, the why, and the where of the great stone book 



laid open to his eye, to read aright the record of the rocks, he must call 



in to his assistance at least the learning of the physicist, the chemist, and 



the biologist, if he be not which, in our present and ever growing state 



of knowledge is practically impossible a physicist, a chemist, and a 



biologist himself. But as it would be evidently impossible for any one 



man to be thoroughly skilled in all these branches and their various 



ramifications at one and the same time, the advanced and advancing 



geologist of to-day carries out the following special plan, when engaged 



in the study of any tract of country. He secures the cooperation of a 



number of specialists, persons who have devoted their time and attention 



more particularly to the study of distinct sections of science, so that 



the highest skill shall investigate for him the several parts of the work, 



and thus individual bricks will be contributed to the edifice which 



the geologist desires to erect. To this end he is aided by at least a 



chemist, who analyzes for him his rocks, his metallic ores, his marls, 



or his soils; a zoologist, who studies the animals found in the section 



of country gone over; and a botanist, who turns his attention to the 



plants discovered in the district traversed. If he desires to carry his 



investigations still further, or if the particular section of country over 



which his labors extend requires that he should do so, he calls in to his 



assistance individuals who have turned their attention to particular 



branches of chemistry, of zoology, or of botany. Thus, insects may 



abound in his field of work, and the farmers will like to know something 



about the ravages they commit upon the crops; or, vegetable diseases 



may afflict those crops ; or, the rocks may be of a kind made use of in 



building ; or, remarkable kinds of deposits, of great interest to science or 



of value in the arts, may occur. In all of these, or any similar cases, it 



will be necessary that the subjects should be investigated by competent 



observers, and they must be found, and their cooperation secured. Where 



the geology alone, as restricted by the boundaries which limited it a few 



years back, is considered, but few of these specialists will be required to 



assist. But, at the present day, and, more particularly, as is the case 

 vol. 1. 55 



