Ber! 
larger and larger. While the embryo grows from 62 mm to 220 mm 
in length (31/, times), the villi increase from 33760 to 1148850 
(35 times) in number. By what process this great increase takes 
place is difficult to determine definitely by means of direct observ- 
ation or from examining single sections. I, therefore, resorted to 
the more definite method of reconstruction, and applied it to the 
human intestine. 
Figure 1 is from a reconstruction of the pig’s intestine after the 
villi are well formed. It is seen that the villi are of unequal sizes, 
some being very large and others quite small. At the point A and B 
there are clusters of very small villi. 
A more careful and systematic study of the villi of the human 
embryo was undertaken after I had established their. mode of growth 
in the pig. I employed for this purpose the series of embryos which 
had already been used by Dr. Matt in his study of the development 
of the convolutions of the intestine’). The models of the loops of 
the intestines of these embryos proved to be of the greatest service 
to me, as it enabled me to locate definitely in the intestinal tract any 
one of its sections. 
The following table gives the principal data regarding these embryos: 
Table giving the Measurements in Millimeters of the 
Human Embryos studied. 
peel ase la E e | 82%. | 3 
pe | mee || der ee 
Er: BR: SAS | 5.2. #55 SoSe 
ar Hea | Of | 282 | see | Lee | gees 
Bo Soo | Dear see Page Fand 
fete py R|N. DB & a | AB a Ae 
| 
Xe 17 14 9,1 ilk Smooth None 
Wis 424 33,9 1,2 Folds None 
XLV | 28 19 52 1,3 Folds None (?) 
XXXIV | s0 | 60 | 366 3,6 Villi 38 50 068 
XLVIII | 130 | 110 | 474 6,7 Villi 104 330 283 
A |240 | 115 | 1105 9153 Vaal 81 | 805 545 
The numbers of these embryos are those employed by Dr. Maun 
in the publication just referred to, and will serve to aid the reader 
in referring to the illustrations given by him. Only in embryos XXXIV, 
XLVIII, and A, are villi present in the intestine. The number of 
villi in each embryo was estimated by counting the number of villi 
1) His’ Archiv, 1897, Supplement-Band. 
