2 rj&EPARATION AND MOUNTING 



which he should be familiar, so as to be able to speak with 

 some degree of certainty of the nature of the tissues demon- 

 strated by them. 



It is now, therefore, intended to give the reader a list of 

 these aids, arranging them according to the effects which it 

 is desired to produce. Strieker observes, " that it is to be 

 borne iu mind that it is impossible to say of any fluid that 

 it constitutes an indifferent, i.e., neutral, medium for fresh 

 tissues of all kinds. In all instances we must be prepared 

 for changes taking place." He gives, however, a list of 

 fluids to which structures are generally most indifferent, i.e., 

 in which least alteration may be detected under examina- 

 tion while fresh, viz. : 

 - 1st. Fluid of the aqueous humour. 



2nd. The serum, of the blood. 



3rd. Amniotic fluid, very fresh, in which a little iodine 

 hj,s been dissolved, making it of a faint yellow tint. 



4th. Very dilute solutions of neutral salts, such as phos- 

 phate and acetate of soda and potash, &c. 



It is scarcely within the power of any one observer to 

 have largely used or tested the whole of the processes here- 

 inafter to be mentioned. The writer therefore freely admits 

 his obligations to the treatises of Drs. Beale and Carpenter, 

 Mr. Quekett and Mr. Fownes, as well as to those of Strieker, 

 Frey, Klein, Schultze, Kiihne, Deiters, Leber, and others, 

 many of whose processes he has personally verified, and of 

 whose manuals, especially those of Beale, Strieker, and Frey, 

 the student is advised to possess himself. He believes also, 

 from his own early experiences, that some short rationale 

 of the intentions of the processes and means of investigation 

 used by well-known workers may be acceptable to the stu- 

 dent, in repeating their experiments before embarking in 

 any of his own. 



These materials and methods may be divided, then, and 

 described according to their effects somewhat as follows ; 

 and it rs in the judicious selection of each one or more of 

 them that the tact and discretion of the student will best 



