16 THE CELL DOCTEINE, 



has enabled proximate physical analysis to become 

 ultimate, 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 

 these observations becomes appropriately the third 

 period. Notwithstanding the imperfect state of in- 

 struments during quite two hundred years after the 

 invention of the compound microscope, a flood of 

 facts was added to oar knowledge of the minute 

 structure of living things, 



Borellus, of Pisa, seems first to have used the mi- 

 croscope in the examination of the higher animal 

 structures, about the year 1656, but his observations 

 were grossly misinterpreted in his attempt to adapt 

 them to the prevailing idea of the day, that diseases 

 were caused by animalculse in the blood and tissues. 

 As a result, he describes pus-corpuscles as animalcules, 

 and even says he has seen them delivering their eggs. 



According to Boerhaave, Swammerdam had recog- 

 nized the blood-corpuscle in the frog in 1658. 



Malpighi,* between 1661 and 1665, had seen the 

 blood -corpuscle in the hedge-hog, had witnessed the 

 circulation of the blood, and had published observa- 

 tions upon the minute structure of the lungs, which 

 he had even compared to a racemose gland,t of the 



* Malpighi, Opera Omnia. London, 1686. 



t Fort, Anatomie et Physiologie du Poumon, considere comme 



