G8 



MANUAL OF HISTOLOGY. 



The form of fibrous tissue that occurs in parallel lamellae is 

 well shown in the mesentery of the frog, and in serous mem 

 branes generally. No great difficulty will be met with in pre- 

 paring this tissue, for it is only necessary to remove it from the 

 frog in the fresh state, acidulate it in a weak (1 per cent.) 

 watery solution of acetic acid, and mount it in glycerine. 



It will be seen that these so-called spindle-cells are really 

 flattened plates, when viewed flat-wise, and generally irregu- 

 larly quadrilateral, though the form varies somewhat in each 

 instance. 



It is not improbable that some which appear spindle-shaped, 

 and lie in the interfascicular spaces, have a double office, one 

 of which is to guard the nutrition of the tissue, and the other 

 to form a partial lining of a lymphatic channel. The researches 



FIG. 26. Connective tissue in the mesentery of the frog. 



of Klein tend to establish this double relation, for they show 

 that these corpuscles lie in the walls of the tymphatic radicles, 

 which are themselves in direct communication with the perito- 

 neal cavity by breaks in the endothelial connective-tissue cor- 

 puscle coating and in actual apposition with the endothelial 

 elements of the serous membranes. 



During the last few years there has been a tendency to regard the serous 

 membranes, especially such as have large openings and slight reticula, as 

 having no connective-tissue corpuscles, other than the endothelial, which form, 



