96 TISSUES OF THE NERVOUS SYSTEM. 



lated fibres which are distributed to the bloodvessels will be 

 described elsewhere.) 



Nerves of the Peritonaeum. For the demonstration 

 of the fine fibres of the peritonaeum of the rabbit, the follow- 

 ing is the best method : Three drops of concentrated acetic 

 acid are added to twenty cubic centimetres of distilled water. 

 To this mixture five drops of half per cent, solution of gold 

 is added. The fresh peritonaeum is immersed in the solution, 

 and allowed to remain exposed to the light for several days 

 until it becomes darkly stained. Very instructive prepara- 

 tions may be obtained by preparing in the same way the fold 

 in the peritonaeum, which stretches backward and to the left, 

 from the diaphragm to the upper surface of the stomach, close 

 to the cardia. 



Nerves of Unstriped Muscular Fibres. The bladder 

 of the frog, the small arteries of the same animal, the muscular 

 coats of the intestine, or of the vagina of the rabbit, may be 

 employed. The following methods are applicable : As regards 

 the bladder of the frog, the previously described method of pre- 

 paring the muscular fibres themselves, also serves for the de- 

 monstration of their nerves. In the bladder of mammalia, the 

 mixture of acetic acid and gold, mentioned above in relation to 

 the preparation of the nerves of the peritonaeum, answers well. 

 After the preparation is sufficiently stained, thin shreds of 

 muscular tissue are stripped from the external surface of the 

 swollen membrane, and prepared in glycerin. In the large 

 arteries of the mesentery of the frog, the method already em- 

 ployed for the demonstration of the non -medulla ted nerve 

 fibres of the mesentery generally, is to be used. The relatively 

 large arteries of the frog (as, e. gr., those of the root of the me- 

 sentery) can, as a rule, be advantageously prepared by placing 

 them for five minutes in half or one per cent, acetic acid, and 

 then either allowing them to stand in the gold solution twenty 

 to thirty minutes, or transferring them to chromic acid solu- 

 tion of one-tenth per cent, for from thirty minutes to an hour. 

 For the un striped muscular fibres of the intestine, uterus, etc., 

 sections of frozen organs may be treated with acetic acid and 

 gold, or chromic acid, in the same way. Finally, small por- 

 tions of the same tissues may be steeped in gold solution, 

 washed in distilled water, treated with tartaric acid, hardened 

 in alcohol, and employed for the preparation of sections. The 

 facts thus demonstrated maybe summed up as follows : Nerve 

 trunks of various size run in the sheaths of connective tissue 

 which lie between the muscular bundles. These trunks consist 

 either of non-medullated fibres, or of medullated, or of both 

 kinds mixed, and form a plexus with wide meshes. In this 

 (which may be termed the principal plexus) the ganglion cells' 

 which have been already described are intercalated. Its nerves 



