. Contributions to embryology. Embryology. 470 ON THE ORIGIN AND EARLY DEVELOPMENT We first attempted to ]M-event the down-growth of lymiihaties by inserting the tip of a porcupine (luill into the angle formed by the duct of Cuvier and posterior cardinal veins in an embryo of 3 days, a stage at winch this region is situated ante- rior to the shoulder. However, when such embryos were examined two or three days later it was found that this wedge had in no way interfered with the normal development, for the veins were present in their normal position beneath the shoul- der, while the plug had rem
. Contributions to embryology. Embryology. 470 ON THE ORIGIN AND EARLY DEVELOPMENT We first attempted to ]M-event the down-growth of lymiihaties by inserting the tip of a porcupine (luill into the angle formed by the duct of Cuvier and posterior cardinal veins in an embryo of 3 days, a stage at winch this region is situated ante- rior to the shoulder. However, when such embryos were examined two or three days later it was found that this wedge had in no way interfered with the normal development, for the veins were present in their normal position beneath the shoul- der, while the plug had remained in the neck region anterior to the shoulder. As might be expected, normal lym])hatics were i)resent over the side and connected with the deeper plexus in a normal manner. Our next operation consisted in making a gap which would isolate the side region from the region associated with the veins beneath the shoulder. This was effected by removing the wing-bud and destroying a number of adjacent Fig. 5.—Normal chick of 55 days, with superficial lymphatics injected with India ink. Compare witli figure 6. X 12. Fio. 6.—Chick from operation 2, with superficial lymphatics injected. Embryo was operated on at 2 days 23 hours. Somites 17 t<) 20 were dissected away and the wing-bud removed. Three days later (when the chick was 5 days and 18 hours old) the egg was reopened and the lymphatics injected. Comparison with figure 10, which shows the superficial lymphatics of a normal embryo of the same stage of development, shows clearly that the side region of the operated chick has been effectually isolated from the deep anterior point of origin. In sjiite of this fact the lymphatics of the side region have developed normally. X 12. Fio. 7.—Chick of 2 days hours which died soon after operation (operation 3). Six somites (22 to 27) wore dissected away together with the body-wall opposite them. The tail-bud posterior to somite 32 was cut off. X 12. The wing-bud was s
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