400 



coat. When the smaller arteries are isolated by boiling in KOH or 

 by macerating in bicarbonate of soda beautiful baskets of reticulum are 

 demonstrated. The net-work of fxbrils in the liver, as described by 

 Fleischl (LuDWiCi's Arbeiten, 1874), and the net-work of fibrils in 

 bone, as described by Heebert E. Smith (Zeitschrift für Biologie, 

 1883), are undoubtedly reticulum fibrils. 



The arrangement of the reticulum in the tendon is very inter- 

 esting. Tendon bundles of the first order (from the rat's tail) have a 

 net -work of reticulum around them. When the whole tendon is 

 treated with acid or with alkali the collagen swells and the reticulum 

 bundles are arranged in hoops which cause constrictions. So also in 

 tendon bundles of the second order. And finally the constrictions 

 around white fibres as first described by Henle are due to individual 

 reticulum fibrils. The constriction is by no means always circular, 

 but may be oblique as described by Ranvier, and from the constricting 

 fibrils, fibrils frequently arise which anastomose with the surrounding 

 reticulum. When the reticulum is removed by digesting the tendon 

 for a long time with trypsin, or by combing (tearing), the constrictions 

 around the fibres can no longer be demonstrated. Moreover in the 

 omentum which is formed almost altogether of white fibrous tissue 

 very few constrictions are seen. 



Chemical analysis shows that reticulum yields no gelatine. From 

 ^/o a kilo of mucosa from a dog's intestine not a trace of gelatine 

 could be obtained. 



When reticulum is isolated it is liable to clump together into a 

 granular mass which may be separated into fibrils by pressing upon the 

 cover glass. 



Reticulum is not highly refractive; elastic tissue is. When di- 

 gested with papoid the interior of elastic tissue will break up, first 

 into irregular particles which then become wholly soluble leaving only 

 the membrane. Later (several days) the membrane also breaks down. 

 Reticulum is very resistant and is not affected by papoid for several 

 days. It does not break down as yellow elastic tissue does, but 

 disappears much as the membranes of elastic fibres disappear. 



White fibrous tissue is not affected by either trypsin or papoid; 

 elastic tissue is affected by both, and with the latter the membranes 

 can easily be demonstrated. 



The micro-organisms that dissolve the elastin and not the mem- 

 branes will not affect reticulum, even after months. 



Reticulum fibrils anastomose; so do yellow elastic tissue fibrils; 

 neither are destroyed by acid nor alkali; neither yield gelatine; both 



