36 STUDIES ON THE LONGITUDINAL MUSCLE OF THE HUMAN COLON. 



Following this, other citations are found, but only of a general nature, such as 

 those made by Oppel (1897), Maurer (1902), Ellenberger and Baum (1909), and 

 Nagy (1911-12). Then Broman (1911) gave a more detailed account of the growth 

 of the taeniae. His statement is longer than Baginsky's and bears the added feature 

 of setting forth the human taenia?, while. Baginsky dealt only with the lower animals. 

 Broman's account in his Handbook (p. 352) is as follows: 



"Bis zur Geburt bleibt gewohnlich auch im Colon die Langsmuskelschicht ringsum 

 kontinuierlich. Bei der im extrauterinen Leben folgenden starkeren Ausdehnung des 

 Colon wird aber diese Muskelschicht in drei parallelen Muskelbiindeln zersplittert, die 

 durch immer grosser werdende Zwischenraume von einander getrennt werden. Die wer- 

 dende Lage dieser Langsmuskelbtindel wird schon im vierten Embryonalmonat durch 

 gef iisshalt ige Mesenchymverdickungen markiei t. ' ' 



More recent citations are made by F. T. Lewis (1912), F. P. Johnson (1913), 

 and Sisson (1914). Sisson dealt with the taeniae in domestic animals only, and 

 Johnson merely referred to them in his study of the mucosa of the human intestine. 

 Lewis, however, has set forth their appearance very definitely. His account is 

 found in Human Embryologij (Keibel and Mall, vol. 2, p. 396), in which he states: 



"At 42 mm. it (the circular muscle) is found throughout the colon. The longitudinal 

 layer appears as a crescentic condensation along the mesenteric attachment of the trans- 

 verse colon at 75 mm. In the transverse colon at 99 mm. the mesenteric taenia is still the 

 most prominent part of the longitudinal muscle, but the other two tamiee are indicated. 

 There is probably a thin layer of longitudinal muscle in the intervals between the teenise." 



MATERIAL AND METHODS. 



This study was confined essentially to the human colon and the results are 

 applicable chiefly to this type. But in order to study as closely as possible some of 

 the minute changes and variations attending early growth, especially the appear- 

 ance of the longitudinal fibers, embryos of different animals were utilized. The 

 most useful of these was found to be the pig, since an abundance of this material 

 was at hand, and it was thus possible to collect a closely graded series and to vary 

 its preparation. The best staining results were obtained by using Mallory's phos- 

 phomolybdic-acid preparation, which differentiated the muscle fibers with a good 

 degree of definiteness. Human fetuses of the following stages of development were 

 studied: 33 mm., 40 mm., 50 mm., 70 mm., 90 mm., 105 mm., 110 mm., 120 mm., 

 125 mm., 145 mm., 160 mm., 180 mm., 185 mm., 190 mm., 200 mm., and new-born. 

 Several of the smallest were prepared whole, and from the others the colon was care- 

 fully removed and two sections, 6 and 8 mm. long respectively, were taken from 

 the two ends (caecal and rectal). Three sections were taken from the older speci- 

 mens, one each from the ascending, transverse, and descending portions. All 

 were sectioned serially and stained by the Mallory method. In addition, the fol- 

 lowing series from the collection at the Carnegie Laboratory of Embryology, Balti- 

 more, was also carefully studied, and these specimens will be referred to herein as 

 C. C. (Carnegie Collection). 



