chap, i.] Introduction. zi) 



it is to combine the separate observations and to fashion what 

 has been seen bit by bit into a clear and connected repre- 

 sentation. 



It appears then that progressive improvement of the micro- 

 scope was not in itself sufficient to ensure the advance of phy- 

 totomy. It would not indeed be too much to say, that the 

 progress which microscopic anatomy made step by step with 

 the aid of imperfect instruments repeatedly gave the impulse 

 to energetic efforts to improve them. Only practical micro- 

 scopists could tell where the real defects of existing instruments 

 lay; it was their anxiety to make them more manageable, their 

 constant complaints of the poor performance of the optical 

 part — complaints loudly expressed, especially at the end of the 

 previous and the beginning of the present century, which urged 

 the opticians to turn their attention to the microscope and to 

 endeavour to make it more perfect. Moreover, essential im- 

 provements in the instrument were made by microscopists 

 themselves. Thus Robert Hooke was the first who in 1760 

 gave the compound microscope a form convenient for scien- 

 tific observation, and Leeuwenhoek developed the powers of 

 the simple microscope to their highest point. The modern 

 microscope is greatly indebted for its perfectness to Amici ; nor 

 ought the name of von Mohl to be omitted here, who invented 

 improved methods for microscopic measurement, and in his 

 work * Mikrographie ' (1846) on the construction of the micro- 

 scope gave many practical hints to the opticians. 



We shall not then make the most important advances in 

 the anatomy of plants depend as a matter of course and quite 

 passively on the history of the microscope ; they were deter- 

 mined here as in other parts of botany by a logical necessity of 

 their own ; here as elsewhere we have to fix our eye on the 

 objects pursued by successive enquirers. If for this purpose 

 we cast a glance over the history of the subject, it will appear 

 that its founders in the latter half of the seventeenth century, 

 Malpighi and Grew, were chiefly bent on determining the con- 



