510 Caroline McGill. 



The possibility that muscle protoplasm may surround the con- 

 nective tissue strands and thus be continuous from muscle cell to 

 muscle cell must not be forgotten. The sarcoplasm between the myo- 

 jSbrillse is extremely hard to differentiate. A small amount of it 

 may continue along the collagenous fibers and still not be seen 

 in preparations. The collagenous fibers between the muscle cells are 

 surrounded by protoplasm during development. In a few places 

 this was seen in the adult. Where there is such an arrangement, the 

 collagenous strands with surrounding protoplasm do represent true 

 cell bridges. 



A number of investigators have described a smooth muscle syn- 

 cytium for adult muscle, where the fibers are united by wide 

 protoplasmic strands. These references have been abstracted in the 

 literature review. Drasch, 1895, in the skin glands, and Schaper, 

 1902, in the mesentery of Urodela, Kohde, 1905, in a number of 

 vertebrates, and McGill (1), 1907, in the pig, have all described such 

 syncytia. 



Among Amphibia rather complete syncytia were found in the 

 urinary bladder and the digestive tract of JSTecturus and frog. Such 

 an anastomosis is shown in Fig. 7, drawn from the intestine of 

 !Necturus. 



In the alimentary canal of chicken only occasionally are there 

 marked side anastomoses of the fibers, though end to end union is 

 common. 



In mammals marked side anastomosis of muscle fibers was observed 

 in some regions in the pig, dog, cat and man. In some of these 

 forms it is very pronounced, in others it is only occasionally met with. 

 In the muscularis muscosse of the small intestine of the pig is the most 

 complete syncytium among the mammals studied, Fig. 14. 



The muscle syncytium of the digestive tract of adult pig is made 

 up of the much elongated muscle nuclei, each surrounded by a granu- 

 lar protoplasmic reticulum, and outside of this a layer of myo- 

 fibrillse embedded in clear protoplasm, Figs. 14, 15. The myo- 

 fibrillse are mainly arranged in spindle-shaped bundles, but from these 

 bundles many of them pass in broad end and side anastomoses, into 

 neighboring groups. 



