5f36 H. LYSTER JAMESON, Auatomy and Histology of Thalassema. 



rig. 21. A piece of the ventral wall of the intestine showing the 

 origin of the collateral intestine, cleared in oil of cloves and examined 

 from inside; c.gr ciliated groove, c.i collateral intestine, o opening of 

 the collateral intestine into the ciliated groove , / furrows outside the 

 lips of the ciliated groove which come together to form the secondary 

 groove, s.gr. From this sketch it is clear that the collateral intestine 

 is simply a part of the ciliated groove, shut off from the cavity of the 

 intestine except at the ends, by the union of its two lips. 



Pig. 22. Posterior end of the collateral intestine, examined as in 21 ; 

 letters as in Fig. 21. The only difference is that the ciliated groove runs 

 forward for a short distance in front of the opening (c. gr'), then ending 

 as in Fig. 21, by the fusion of its walls. 



Plate 30. 



Fig. 23. Sections of the origin of the collateral intestine , drawn 

 with the camera lucida. In A the ciliated groove alone is present, B 

 and C cut the opening where the groove is actually going over into 

 the collateral intestine, D and E show the collateral intestine with 

 the secondary groove, letters as in Fig. 21. The sections are followed 

 from before backwards. 



Fig. 24. Sections of the posterior end of the collateral intestine, 

 followed from before backwards, drawn with the camera lucida. In A 

 only the collateral intestine and secondary groove are present, B cuts 

 the transverse ridge formed by the union of the lips of the ciliated 

 groove. C, D and E are sections of the region where both groove and 

 collateral intestine are present , E being just on the margin of the 

 opening. F cuts the opening itself, and in G we have only the ciliated 

 groove. 



Fig. 25. The vascular inng embracing the crop (cr), d. v dorsal 

 vessel, n. i. a neuro-intestinal anastomosis. 



Fig. 26. Blood vessels of an individual in which only one iialf 

 of the intestinal ring is rej)resented ; oe oesophagus, cr crop, int in- 

 testine, d.v dorsal vessel, v.v ventral vessel, n.i.a neuro-intestinal 

 anastomosis, m. r muscle ring. 



Fig. 27. Another example of variation in the relations of the 

 vessels; letters as in Fig. 26. 



Fig. 28. The relations of the ventral and dorsal mesenteries to 

 the oesophagus, showing the false dissepiment made by the ventral 

 mesentery. (As seen when the animal is dissected from behind for- 

 wards.) For this drawing I am indebted to my friend and colleague 

 Herrn Wladimir Redikokzew. The oesophagiis is coloured brown, the 

 ventral nerve chord yellow; d.m dorsal mesentery, v. m ventral mes- 

 entery, oe oesophagus, m free posterior falciform margin of the ventral 

 mesentery, m' continuation of the same along the mid-ventral line, where 

 the mesentery carries the ventral blood vessel, n. c nerve chord, o opening 

 into the section of the body cavity which is almost cut off anteriorly 

 by this pseudo-diaphragm. 



