282 HOW TO WORK 



p;iper must be quite ignorant of much of the microscopic work of the 

 last five or six years. If he refers to the journals published in Ger- 

 many, particularly to Schultz' Archiv, or to Kolliker's Zeitschrift, 

 or to the Philosophical Transactions of the Royal Society, or the 

 Microscopical Journal, he will soon be convinced he is mistaken. 

 Vague and incorrect assertions of this kind too often find their way 

 into journals in consequence of mere carelessness or indolence upon 

 the part of the editors. 



It is not, however, to be wondered at that the introduction of new 

 and more refined methods of investigation should meet with consi- 

 derable opposition, for in all departments of progressive knowledge 

 are to be found men who seem to consider it their special duty to 

 discover as soon as possible any symptoms of too rapid advance, and 

 oppose them with the utmost vigour. It is to be regretted too that 

 sometimes the innovators and rebels of one period become the 

 obstructives of a later time. Some of the warmest advocates of pro- 

 gress seem to reach a period in their career when they tire of the 

 constant change, and become unable to conquer their instinct to stand 

 still. Regardless of the struggling crowds behind them, they long to 

 rest in a position which they have at last acquired after years of intense 

 labour ; but they ought to remember that by so doing they are consti- 

 tuting themselves the strongest opponents of scientific progress and 

 the enemies of true science, for science can never rest without the 

 greatest danger of retrograding and losing much of w r hat has been 

 already gained. She must, .therefore, have new and vigorous labourers 

 always ready to take the places of any who show the slightest signs 

 of fatigue or longing for ease. 



There are, however, some branches of microscopical enquiry in 

 which it is generally admitted that very high magnifying powers are 

 absolutely necessary. For example, in such investigations as those 

 which have lately been carried on by M. Pouchet and M. Pasteur, many 

 of the more minute organisms can only be seen by a power magnify- 

 ing upwards of 1,000 diameters. Bacteria, magnified i,Soo and 3,000 

 diameters respectively, are represented in pi. LVII, figs. 372 to 377. 

 If still higher powers had been brought to bear upon the specimen, 

 organisms still more minute than any represented in these figures 

 would probably have been demonstrated.* The most minute of such 



* My friend Dr. Child who has paid much attention to the subject referred to, 

 makes the following remarks : "The absolute necessity of using high magnifying 

 power in attempting the solution of some of the problems which now present them- 

 selves to the physiologist is well shown in some of the recent investigations into 

 the development of minute fungi. M. Pasteur has been in the habit of using an 

 object-glass of 350 diameters, seeliis paper in the Annales de Chimie, vol. LXIV. 



