VI PREFACE. 



great extension is in large measure due to the luxuriant 

 growth of the literature that has sprung up round the hge- 

 matoxylin methods of Weigert and the bichromate-of-silver 

 method of Golgi, and which it has been deemed advisable 

 to treat with all possible fulness. 



The Methylen Blue impregnation method has nearly an 

 entire chapter assigned to it. This important process has 

 by no means been brought to perfection, but much has been 

 done already, and the future is full of promise. 



The progress that has been made during the last three 

 years is certainly gratifying, but I must once more complain 

 of the mischief that is done by the method-mongers. The 

 reckless publication of crude or needless histological methods 

 is a crying evil. The really useful matter that is published 

 is smothered in a sea of rubbish, and the investigator is 

 obliged to devote to the acquisition of such new technical 

 knowledge as he may require very much more time than 

 would suffice if he were only unimpeded. Some idea of the 

 magnitude of the evil may perhaps be gleaned from the fact 

 that this book has now been out of print for many months, 

 the mass of literature that it has been necessary to digest 

 for the purpose of a new edition being so great that the 

 appearance of the work has been delayed far beyond the 

 contemplated time. 



It is useless to remonstrate with the persons of whom I 

 am complaining ; they cannot grasp the fact of their igno- 

 rance, and cannot be brought to see that nobody heeds 

 them. I would appeal earnestly, therefore, to those with 

 whom the power lies to put an end to this nuisance. It 

 surely is not too much to ask that the editors of the periodi- 

 cals devoted to these matters should refuse to publish pro- 

 cesses that are not demonstrably new, and that do not make 

 out a good claim to be useful. 



NYON, SWITZERLAND ; 

 August, 1893. 



