554 Franklin P. Johnson. 
here they are rather indefinite and uncertain. In the upper third 
of the duodenum and in the uppermost part of the jejunum at 
78 mm. no evidences of the circular folds could be found, but 
they are distinct in the mid region of the small intestine. They 
are quite regularly placed, averaging .78 mm. distant from each 
other. In height they vary from .17 mm. to .23 mm. At the 
extreme lower end of the ileum at this stage, no folds are present. 
None were found in the duodenum at 120 mm. (embryo 203). 
Slight folds are present in the lower end of the ileum at 134 mm. 
In a distended portion of the small intestine at 145 mm. (mid 
region), circular folds were found which measure .06 mm. in 
height, and at an average distance of 1.87 mm. apart. In the 
duodenum at 240 mm. two circular folds were found at distances 
of 4.7 mm. and 7.1 mm. below the pyloric orifice. In the mid 
region of the small intestine at this stage, folds were found which 
vary from .25 mm. to .51 mm. in height, and at a distance averag- 
ing 1.3 mm. apart. 
TABLE 3 
DvuoDENAL EPITHELIUM (UPPER THIRD) 
ng val 
THICKNESS! OF DIAMETER OF) 
EMBRYO SURFACE EPITHELIAL | VILLI Yea poten 
EPITHELIUM TUBE 
Length In Gell |i mm.2| In mm. Height? eye Length‘ vane | Length® | ers 
in mm. Layers in mm. bases” in mM. | jn mm. in mm. | in mm. 
| 
7:5| 23 | 086| 077 | | 
16. a “ Mle © | | 
19. 24 | .048|. .194 088 | .11 
22.8; 12 | .019| .299 1250 NEA oae 
24 i! .024 »36 .193 mp a | 
30 ? a ee oid gals 
37 1 .024 | 58 23 13. 
42 1 021": 565 £2) ea 
55 1 .019 .95 A260) eal 048 06 
78 1 .016 | 1.038 .29 .11 | .088 04 07 | .033 
120 1 L015 \ ale 14 ol | es) 09 .06 12 | 031 
187 1 O15 | 2h AT | .09 14 05 .22 | 0381 
240 1 (O15 |) 3.5 Gtaye o) lll 12 05 .30 .036 
| 
10n tops of villi when present. at ; 
2 Tallest. 
3 Average of a number of measurements. 
4 Longest. 
5 Vertical distance below bottoms of intestinal glands. 
* Vacuolated stage. 
