Law states (Vol. II. p. 347) that in cattle and swine invagination of the large colon is almost impossible owing to the relation of the bowel with the layers of the mesentery. The anatomical arrangement is opposed to the formation of invagination, yet this accident is not uncommon in cattle and swine. The small intestine can be invaginated into the cæcum or into itself. The cæcum may become invaginated, or it may pass into the colon or rectum. Cartwright, _Veterinarian_ (1829), reports a case of invagination in a bull calf, and Youatt gives particulars of a similar case which was followed by sloughing and discharge per anum of the intussuscepted portion of bowel. (See also Möller and Dollar’s “Regional Surgery,” p. 328.) =Causation.= This variety of colic is due to a number of somewhat obscure causes. In a general sense we may say that anything which increases intestinal peristalsis increases the risk of invagination. The accident may follow intestinal congestion, but is most frequent in animals suffering from intestinal worms, or in animals used for heavy work. Under the influence of violent tractive efforts the peristaltic movements are stimulated, and the intestine being in an oblique position on a plane inclined backwards, the contracted portion may slip into the dilated section behind it. [Illustration: $1] Invagination may also occur without any apparent cause, even in animals standing in the stable. =Symptoms.= The attack always occurs suddenly, develops rapidly, and is of an extremely grave character. Colic comes on while the animal is working, moving about, or resting, according to circumstances, and at first resembles that due to congestion. It afterwards becomes very violent; the animals paw, stamp, show great uneasiness, throw themselves violently down, and rise suddenly, only to again lie down as before. The face expresses anxiety, suffering and depression; the tail is often kept lifted, and efforts are continually made to defæcate, mucus being passed. By passing the hand into the rectum the invagination may occasionally be discovered.