50 Mr Eichholz, On Urobilin. [Jan, 30, 



Structure of Stomodcmmi. The storaodseum forms a muscular 

 oesophagus leading upwards and forwards into the gut. It con- 

 sists of a muscular tube lined by a simple low epithelium covered 

 internally by a cuticle. 



The muscle fibres are striated ; they are arranged in a single 

 layer of annular fibres and a pair of longitudinal muscles. 



The jjroctodceimi is the terminal vertical or recurved portion 

 of the gut. It is narrow, flattened laterally and lined by a 

 low cubical epithelium and cuticle. Its basement membrane is 

 especially well developed. 



Structure of basement membrane of the gut. This is the actively 

 contractile organ which brings about peristalsis. Its structure is 

 peculiar and it forms a membrane which is continuous over the 

 whole mesenteron. This membrane is thin, hyaline, structure- 

 less, very tough, and very elastic, as is shown in teasing, and 

 highly refractive. In it are embedded protoplasmic strands which 

 are presumably the contractile elements. These are narrow 

 flattened bands arranged in two series, a longitudinal and a 

 circular. The longitudinal bands are continuous for at least 

 half the length of the gut, probably the whole ; whether the 

 circular bands are annular or spiral we have not determined. 



The circular bands are rather broader and more closely set 

 than the longitudinal, being separated by intervals two to three 

 times as broad as themselves. Each band is enclosed by a 

 splitting of the hyaline membrane which sends a sheath both 

 internal and external to the band. In transverse section the 

 latter therefore appears as a dark oval patch lying embedded 

 in the hyaline substance, and resembling a nucleus of the latter. 



The bands show indistinct longitudinal fibrillation in places ; 

 and also a faint indication of irregular cross striation ; these 

 markings however are probably due to folding. 



We have not succeeded in finding any traces of nuclei in the 

 basement membrane. Where the longitudinal and circular bands 

 cross one another, they appear to run straight on without being 

 specially connected. 



(3) On Urobilin. By A. Eichholz, B.A., Emmanuel College. 



In this communication a new method of urobilin extraction 

 was described, by which the pigment is preserved in the state 

 of chromogen. The properties of Urobilin in normal and febrile 

 urines were recapitulated in order to compare urobilin with the 

 reduction products from bilirubin and hsematin. The communi- 

 cation was then devoted to a description of experiments devised 

 to settle the question as to the possibility of artificial production 

 of urobilin from bilirubin and hsematin. After pointing out how 



