INTRODUCTION. 3 



1723), are generally looked upon as the fathers of microscopical anatomy. 

 The first of these made observations on the circulation of the blood, on 

 the glands and lungs ; the second, endowed with indefatigable industry, 

 saw for the first time many of the constituents of the organs of the body, 

 with tolerable distinctness too, although aided by very imperfect instru- 

 ments. But the additions which Leeuwenhoek made to science, in keeping 

 with the curiosity-loving spirit of the time, partook less of the nature of 

 discoveries according to a definite principle, than of mere detection of 

 strange and wonderful things, where the unaided eye had previously seen 

 nothing. The infancy of microscopical anatomy is in fact represented in 

 him. Indeed, the exertions of the Dutch seem just devoid of that which 

 so characterised the investigations of the Frenchman Bichat,* namely, 

 that effort to combine units to a scientific whole. If we now associate with 

 these fc\vo names those also of Swammerdam (1637-1685), and Ruysch 

 (16381734), as the discoverers and developers of our present mode of 

 injection, we shall have reached the close of the first epoch of histological 

 study defined by the discovery of the microscope. 



The instruments of that day were, however, most imperfect, so that 

 Leeuwenhoek used simple lenses only. Hence, it is not surprising that in 

 the hands of his successors, these microscopes, so difficult to manipulate, 

 and so liable to deceive, became a frequent source of error. This explains 

 the fact that Bichat preferred laying the foundations of his general 

 anatomy without their aid. 



After this there followed a long period of inactivity in histological 

 research, reaching far into the nineteenth century, when the science 

 received fresh impetus from the brilliant discoveries of our own schools. 



REMARKS. Marcello Malpighii. Opera omnia. Lond. 1686 ; and Opera posthuma. 

 Lond. 1697-.. .2. The works of Leeuwenhoek may be found in the Philosoph. Transact., 

 and in his Opera omnia. Lugd. Bat. 1722. Arcana naturae detccta. Delph. 1695. 

 Continuatio arcanorum naturce detectorum. Liigd. Bat. 1722, &c. 



3. 



A new era in histological research was now ushered in by the discovery 

 of achromatism in the middle of the last century, and by the construction 

 of achromatic object-glasses for the microscope. The first of these are 

 said to have been made by a Dutchman named van Deyl, and a German 

 optician of the name of Fraunhafer, in the years 1807 and 1811. Thus 

 the microscope was transformed from the clumsy and deceptive imple- 

 ment of the last century into the elegant and accurate instrument of the 

 present day. 



And now, in all the enthusiasm of novelty, the improved microscope 

 became the means of adding discovery to discovery in the hands of many 

 excellent German observers, so that an insight into the essential nature 

 of the tissue-elements, and of their combination to form the various 

 tissues, was gained in an inconceivably short time. It may suffice here, 

 in speaking of the founding of modern histology, to mention the names 

 of JZhrenbe.rg, Mutter, Purkinje, R. Wagner, Valentin, and Henle. Be- 

 sides these, many others might be added, of younger observers, who have 

 since distinguished themselves as developers and furtherers of the science. 



Histology without the microscope had had a Bichat among its students ; 

 but the newer science was fortunate enough at its very outset to undergo, 

 at the hands of Th. Schwann, the most searching and energetic elabora- 



