THE CELL DOCTRINE. 15 



Stelluti published a description of the parts of a bee 

 he had examined with the microscope, and although 

 George Ilufnagle is said to have published in Frank- 

 fort, in 1592, a work upon insects, illustrated by fifty 

 copper plates, it is highly probable that these, as well 

 as very many most important observations made after 

 the invention of the compound microscope, were 

 made with the simple instrument.* 



It is impossible to estimate the assistance the 

 microscope has been to us in opening up the minute 

 structure of animals and vegetables, and in thus af- 

 fording a reliable basis on which to build a doctrine 

 of organization. Prof. Huxley says, "The influence 

 of this mighty instrument of research upon biology, 

 can only be compared to that of the galvanic battery, 

 in the hands of Davy, upon chemistry. It has ena- 

 bled proximate analysis to be ultimate."^ But it is 

 more than this. Since, as he correctly states, it has 

 enabled proximate physical analysis to become ulti- 

 mate, it corresponds, not to the galvanic battery 

 alone, but to all the appliances made use of in ulti- 

 mate chemical analysis. 



The time prior to the invention of the compound 

 microscope may be considered as the first period in 

 histology ; that between this date and that of the ob- 

 servations of Schleiden and Schwann (1838), inclu- 

 sive, the second period ; while the time subsequent to 



* For an interesting and exhaustive history of the invention of 

 the compound microscope, see Das Mikroskop, Theorie, Gebrauch, 

 Geschichte und gegenwartigcr Zustand desselben. Von P. Harting 

 In drei Banden. Braunschweig: 1866. Dritter Band, ss. 11-35. 



f Huxley, loc. citat., p. 290. 



