A study of the conditions under which agonic invagination of the intestine occurs will not be out of place in considering the etiology of intussusception. Agonic invagination is very much more common in children than adults, the proportion being, according to [Hermann] Nothnagel, one to fifty. [Luther Emmett] Holt says that agonic invagination is met with in 80 per cent. of the post mortems on infants.