378 CHAPTER XXX. 



(rZ) Axis-cylinder-and-protoplasm impregnations, consist- 

 ing chiefly of the methods of GOLGI (the sublimate method 

 and the three bichromate of silver methods), and certain gold 

 methods. 



A large proportion of the methods used in the study of 

 nerve-tissue in peripheral organs have already been exten- 

 sively treated of in the chapters on " Methylen Blue/' on 

 " Impregnation Methods/' 011 " Tegumentary Organs/' and 

 011 " Muscle and Tendon." The reader should therefore 

 bear in mind that a considerable part of the subject properly 

 comprehended under the term " Neurological Methods '' is 

 contained in those chapters, which should be referred to in 

 order to complete the account given in the following pages. 



The remainder of this chapter will be devoted to the 

 special section methods employed for the central nervous 

 system, and to the Cytological Methods of Neurology. 

 Group A of the Anatomical Methods will be given in Chap. 

 XXXI, and Group B in Chap. XXXII. 



For more minute details concerning the dissection and hardening of the 

 voluminous encephala of Man and the larger Vertebrates than can be given 

 here see MERCIER, Les Coupes du Systeme Nerveux Central (1894, Paris, 

 Eueff) ; DEJERINE, Anatomic des Centres Nerveux, Paris, 1895 ; BE VAN 

 LEWIS, The Human Brain ; Histological and Coarse Methods of Research, 

 London, Churchill; and OBERSTEIXER, Anleitungbeim Studium des Baues 

 d. nervosen Centralorgane itn gesimden u. kranken Zustande, Leipzig, 

 Toeplitz. 



SECTION METHODS. 



681. Fixation by Injection. Fixation, in the proper sense 

 of the word, is, of course, out of the question in the case of 

 the human subject. But in the case of the lower animals it 

 is possible to introduce fixing liquids into the living nerve 

 centres by means of injection, thus ensuring a much more 

 rapid penetration of the reagents than can be obtained by 

 simple immersion. This method was, I believe, first sug- 

 gested by GOLGI (Arcli.. Ital. de Biologie, t. vii, p. 30). He 

 injected 2'5 per cent, solution of bichromate of potash through 



