MOTOR END-PLATES. 135 



any other reagent. One or two corpuscles are to 

 be thoroughly isolated and freed from surrounding 

 mesenteric tissue and fat ; placed for ten minutes 

 in silver solution (1 in 200); washed in distilled 

 water, and exposed in glycerine to the sunlight 

 until of a grayish color, when they may be covered, 

 and examined. 



Preparation 10 To complete the study of the 

 Pacinians, sections should be made of them, but as they 

 are very small, it will be best to defer this until some prac- 

 tice has been attained in the art of cutting microscopic 

 sections. A convenient way to prepare them, in order 

 to show the various parts to advantage, is as follows : 

 A very small piece of meso-rectum, containing several 

 corpuscles close together, is cut out (if such can be 

 found ; if not, one or more may he isolated as before), 

 and placed in a small beaker containing 100 cub. cent, of 

 a weak solution of acetic acid (1 in 200), to which about 

 5 c. c. of the ordinary (^ per cent.) chloride of gold solu- 

 tion has been added. The tissue is kept in this, in the 

 light, for three or four days until it has become of a 

 dark violet color; it is then placed for a day in weak 

 spirit, and then in strong, and two or three days later is 

 ready for embedding and cutting. In embedding the 

 piece of tissue, it should be so placed that the corpuscles, 

 at least most of them, are cut as nearly as possible trans- 

 versely. 1 



Preparation 11. The end-plates, or terminal 

 expansions of the motor nerves, are difficult to find, 

 and so soon undergo alteration as speedily to become 

 unrecognizable. On this account it is necessary, in 

 searching for them, to employ only muscles which 

 are absolutely fresh. In mammalia the best muscles 

 to choose for the purpose are those of a lamellar 

 shape and with short fibres, such, for instance, as the 

 intercostals of small animals. The muscular fibres 



1 A description and delineations of the appearances exhibited 

 by the Pacinian corpuscles when prepared in these several ways 

 will be (bund in the ' Quarterly Microscopical Journal'' for April, 



1875. 



