THE SPLEEX IN MONOTREMES. 



stem rarely runs directly into this portion. Usually there 

 is narrowing at the point of attachment, and the connec- 

 tion between the two may be merely a slender fibrous 

 thread. The stem varies from 1.5 to 3 cm. in length and 

 average width .5 cm., while the body varies from 2 to 3.5 

 cm. in length and circumference may reach 5 to 6 cm. 

 This process, as in Platypus, lies outside the lesser sac 

 in relation to the lieno-mesocolic fold, extending caudally 

 towards the pelvis on the left of the distal colon. In one 

 specimen out of a large number examined, I found the 

 left stem included in the lesser sac. The distance between 

 the pear-shaped body and colon may only equal .75 cm. 

 The pancreas is a less mobile organ than that of the 

 Platypus, and in not one of the numerous specimens 

 examined by me did it extend sinistral to the lesser sac, 

 so as to come into relation with the lieno-mesocolic fold. 

 The distal left colon is mobile, having a mesocolon. In 

 one specimen this was greatly narrowed and the length of 

 the distal colon in the abdomen only equalled 7 cm. In 

 another — a male specimen — the pancreas was a " fixed' ' 

 organ and on the right side was adherent to the lobus 

 caudatus. The left or distal colon was fixed dorsally, 

 describing an almost vertical course to the pelvis. In 

 close relation in this specimen, and all fixed dorsally in the 

 left lumbar region, were the left testis, kidney, pear- 

 shaped process of spleen, and distal colon. The pancreas 

 extended but a short distance on the left of the colon and 

 apparently had little influence in the fixation of this struc- 

 ture, since it never extended to the left in relation with the 

 lieno-mesocolic fold. Yet fixation has occurred. In this 

 specimen, as well as the one with a shortened mesocolon, 

 the distal left colon was relatively short; there was a 

 failure to develop, with atrophy of the mesocolon. In- 

 stead of the distal colon from the duodeno-intestinal 

 flexure to vestibule being 28 cm. long — the average adult 

 male length — it only measured 13 cm. 



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