156 



The Structure of Human Umbilical 'Wsicle 



tively. Mayer's exhaustive monograph, which appeared in 1835, re- 

 moved many of these misconceptions; though regarding its functions he 

 says, " ueber den eigentlichen Zweck des Nabelblaschens schweben wir 

 in ganzlicher Ungewissheit." It is interesting to note, however, that 

 most of the early investigators ascribed nutritive and hgematogenous 

 functions to it. 



The following study is based mainly upon eighteen normal human 

 umbilical vesicles in the collection of Dr. Mall, to whom I am greatly 

 indebted for the unrestricted use of his extensive collection of human 

 embryos, and for many helpful suggestions. Besides these normal speci- 

 mens, a number of pathological ones, and some taken from placenta at 

 birth, were examined. They were all stained in alum-carmine" and im- 

 bedded in paraffin. An endeavor was made to set the imbedded vesicle 

 so that its long diameter, which usually lay in the same direction as the 

 remnant of the umbilical stalk, was at right angles to the microtome 

 knife. In all cases in which this was not possible, account was taken of 

 the fact in the study of the sections. 



As the following table shows the size of the vesicles, not including 

 those taken from placenta at birth, varies from one to six millimeters in 

 embryos from 11 to 110 days old: 



TABLE OF EMBRYOS AND ATTACHED UMBILICAL VESICLES. 



The numbered emhryos in the first colunui refer to the cabinet of Dr. Mall. 



Length of Embryo Diam. of Vesicle Approx. Presence of 



in millimetei'S. in millimeters. age in days. tubules. 



Embryos of the Second Week. 



Peters 0.19 0.19 .. None 



vonSpee 0.37 l.OSbyl.O 13 None 



No. II 0.80 1.00 by 1.5 13 Several 



Keibel 1-00 1.00 .. Many 



V. Spee-Gfe 1..54 1.8 by 1.5 13 Many 



Embryos of the Third Week. 



No.12 3.1 1.5bylbyl 13 Several 



Janosik 3.0 3.5 15 No mention 



No. 76 4.5 3.0 19 Many 



No.80 4.5 4.0 19 Some 



Embryos of the Fourth Week. 



No. 18 7 26 None 



No.2 7 7by4.5by4.5 26 Some 



Embryos of the Fifth Week. 



No.187 9 6by4.5by4.5 30 Many 



No. 163 9 5.2 by 3.7 30 Some 



No. 113 — 30 Many 



No.187 10 4 33 Macerated 



Embryos of the Fifth and Sixth Weeks. 



No. 175 13 3.7by3 36 Many 



No. 167 14.5 5.5 by 5.3 38 Many 



No. 5 18.5 4.7by4.5 43 Macerated 



Embryo over Six Weeks. 



No. 33 20 5 by 3 by 3 43 Some 



No.l45» 33 4.5bv4by2.5 57 Few 



No. 176 38 4.8 by 3.6 by 3.5 61 None 



No. 184 50 5 by 4 by 3.9 70 None 



No. 171 60 6.5 by 4.3 77 None 



No. X 110 4.5 by 4 110 None 



