AGENESIS OF THE VERMIFORM APPENDIX. 
By Harry T. MArsHAtt and Ratpu T. Epwarps.' 
(From the Biological Laboratory, Bureau of Science.) 
Variations in the size, shape, and position of the cecum are not 
particularly uncommon, though usually these lie within narrow limits. 
Differences in position, length, and mesenteric attachment of the ap- 
pendix are very common. It is usually stated that the length averages 
from 5 to 8 centimeters, the extremes being between 1 and 33 centimeters. 
According to Treves, four general types of appendix and cecum are 
encountered ; these depend in part upon the shape of the appendix and 
in part upon the degree to which the development of the lateral terminal 
sacculus (haustrum) of the cecum exceeds that of the mesial terminal 
sacculus. The right sacculus is the larger in nine out of ten subjects. 
According to Gegenbaur, the embryonic caecum develops unevenly ; one 
part develops fully and forms the adult cecum, while the growth of the 
terminal portion is arrested at an early stage, leaving a conical tube 
terminating the cecum at the time of birth. This is the condition 
described by reves as the foetal ‘type of appendix. Gegenbaur appar- 
ently considers this the normal condition in the new born, the narrowing 
of the appendix and the development of the right haustrum of the 
cecum occurring subsequently. Quain states that in the great majority 
of cases these changes begin before birth, and this is the prevailing view. 
The embryogeny of the cecum and appendix was carefully studied by 
Kelly and Hurdon (4) in the series of human embryos collected by 
Professor Mall and Mr. Max Brédel at the Johns Hopkins University. 
The cecum first appears at the fifth week of foetal life as a slight 
swelling near the most anterior portion of the intestinal loop. A 
transient process, like the vermiform appendix, appears at the lower end 
of the cecum as a bud, sometimes showing a cavity continuous with that 
of the gut. This structure disappears about the eighth week, leaving no 
trace. The true appendix develops as an extension from the primitive 
cecum, having the caliber of the latter. About the seventh or eighth 
week a primary differentiation occurs into a large, proximal pouch and 
a smaller distal one. The diminution from the larger to the smaller 
* Read before the Manila Medical Society October 1, 1906. 
1061 
