498 Caroline McGill. 



not of the fiber itself. However, in portions of the gland having only 

 scattered muscle cells, he found distinct knot-like enlargements of the 

 fibers, which he attributed to contraction. He also observed that in 

 the contracted fibers, the fibrillar structure is lost, and that such 

 fibers show marked affinity for eosin. 



Schaffer, 1899, studying fresh preparations of the intestinal 

 muscle of the horse, found knot-like swellings on some of the fibers 

 which he considered pathological. In these enlargements no myofi- 

 brillse were oberved. Schaffer, in normal contraction, described the 

 entire fiber becoming shorter and thicker, and at the same time losing 

 its fibrillated structure. 



Heidenhain, 1900, discusses the behavior of the smooth muscle 

 nucleus. During contraction the nuclei become distinctly shorter and 

 thicker. In certain degrees of contraction this is the only change. In 

 very strong contraction, however, the nuclei are variously folded, and 

 tv/isted. If the resting nucleus is very slender, as in the muscle in 

 the blood vessels, it may, when contracted, wrap up into a spiral. 

 Less elongated nuclei, in firm contraction, show various sorts of fold- 

 ing and wrinkling. Heidenhain considers both the "Grenzfibrillen" 

 and the "Binnenfibrillen" contractile elements, though he gives no 

 direct evidence that they are such. 



Henneberg, 1901, studied the smooth muscle of the carotid artery of 

 the ox, both in the resting and in the qontracted condition. When 

 the carotid is cut, the proximal end contracts very firmly, the distal 

 end relaxes completely. Small pieces from any part of the artery, if 

 cut out and warmed, slowly contract, if cooled, relax. By quickly 

 removing very small pieces and throwing them into hot water, Henne- 

 berg was able to fix the tissue rapidly enough to prevent contraction 

 of the expanded muscle. In material so preserved he found two types 

 of fibers; (a) Long, slender, band-like fibers with no myofibrillse, 

 with protoplasm staining deep red in eosin and black in iron-hsema- 

 toxylin. In such fibers the nuclei are long and rod-like; (b) spindle- 

 shaped fibers, thicker in cross-section than type (a), with slightly 

 staining, fibrillated protoplasm and short, thick nuclei. Between 

 these two types he found all transitions. The deeply staining, homo- 

 geneous fibers, he considered the resting; the lightly staining, fibril- 



