1891.] MICROSCOPICAL JOURNAL. 147 



I have left it under a 4 objective, and at the end of an hour have found 

 it still in the field. 



Tliis rotifer sepai-ates its toes literally like pincers, and seizes objects 

 between them as if to get a better hold. The one figured came from 

 Wimbledon Common, and was abundant in some water given me by G. 

 Western, Esq. 



The Work of the Microscope.* 



By p. H. DUDLEY, C. E., 



NEW YORK, N. Y. 



At no period in the history of the microscope have the results of its 

 researches received as much attention as at the present time. The im- 

 portance of the investigations in recent years, by its means, of many of 

 the causes affecting the health and comfort of mankind, is just being 

 recognized by the efficacy of the remedies which have been suggested 

 from a knowledge of the causes. The indications of a new remedy 

 are daily flashed from continent to continent by that unseen agency, 

 electricity, its messages multiplied by the press in all languages and 

 distributed through the land by steam's swiftest trains. These three 

 great inventions of communication and diffusion of knowledge of to- 

 day have carried the tidings to the peoples of all nations, and there is 

 a common interest and thought upon the subject. History does not 

 record a grander spectacle than that of the entire civilized world, 

 brought into sympathy and interest by the investigations of the micro- 

 scope, in search of relief for thousands of its sufferers from some of 

 the occult conditions incident to life. 



Animal or plant life, either of the highest or lowest orders, is sur- 

 rounded by conditions, some favorable to growth, others unfavorable, 

 and whether an animal or plant will survive or perish aside from the 

 inherent vitality depends upon the preponderance of the favorable or 

 the unfavorable conditions of environment. This law is coeval with 

 the existence of life. To ascertain and understand the conditions fa- 

 vorable to the human race has and will always occupy the attention of 

 a lai'ge portion of the more intelligent of mankind. 



Some of the conditions are at once apparent ; others equally im- 

 portant are unseen, obscure, and only discovered by tracing back from 

 the effect to the cause. We experience effects and not causes, and to 

 analyze the former, assigning each to its proper cause, is by no means 

 an easy matter. The first step is to observe the facts, study their rela- 

 tions, and trace the laws controlling them. It is only in this way that 

 any progress has been made, and then oftentimes the real nature of the 

 cause remains undiscovered. 



Jennei''s important discovery of vaccination for small-pox a century 

 ago was not the result of an accident as often stated, but close observa- 

 tion of a series of facts and studying their relations. That small-pox 

 was due to a germ in the system invisible to the keenest vision is of 

 recent demonstration by the microscope. 



* Annual address of the President of the New York Microscopical Society, i8yi, from journal of N. 

 Y. Microscopical Society . 



