kko 



EXPERIMENTAL CHICK EMBRYOLOGY 



I \:q 



Summarj' diagrams cased on a study of over 

 50 Dlastoderms growing in ovo and stained 

 as shown in (a) with a 1:1 mixture of 0.5% 

 Nile blue sulfate and 0.5'?J Neutral red. 

 In (b) is shown the position of the stained 

 band of cells 6 hours later. In (c) (drawn 

 to a somewhat smaller scale than a and b) 

 Is shown the pattern of stained cells 14 

 hours later (20 hours after the original 

 marking as in a) . If (c) be compared with 

 (b) it is to be noted that the end-bud and 

 the neural tube have secondarily acquired 

 the stain and keep it in the oxidized 

 (blue) state. In the region just anterior 

 and lateral to the bases of the omphalo- 

 mesenteric arteries no stain can be seen 

 (presumably it is in the reduced (color- 

 less) state) . The stained regions lateral 

 and parallel to the neural tube are in the 

 lateral plate mesoderm (cf. Pasteels, 

 1937, fig. 18) . No exceptions to this re- 

 sult liave been found. 



Diagrams 

 posterio 

 region ( 

 vaginati 

 the pres 

 the node 

 sion of 

 left to 

 more rap 

 primitiv 

 lying la 



illustrating 

 r "stretching" 

 neural plate) , 

 on through the 

 ence of invagi 



during the ea 

 the streak. T 

 right in the d 

 id and extensi 

 e streak relat 

 teral to it. 



the pronouned antero- 

 of the pre-nodal 

 the absence of in- 

 primitive pit, and 

 nation Just behind 

 rly stages of regres- 

 ime increases from 

 iagraras. Note the 

 ve regression of the 

 ive to marked areas 



Two above diagrams from Spratt 19't-7: 

 Jour. Exp. Zool. 10k -.69 



A -LIVER 



^-MEART 



©-CHORDA 



6-THYROIO 



©-NEPMROS 



X -INTESTINE 



• -ERYTHROCYTES' 



T-MELANOPHORES 



■♦■ SKELETAL MUSCLE 



DISTRIBUTION OF POTENCIES IN THE DEFINITIVE PRIMITIVE 



STREAK BLASTODERM, TESTED UNDER VARIOUS EXPERIMENTAL 



CONDITIONS 



Ectodermal potencies shown on left, mesodermal and en- 

 todermal on right; tliese have not been tested separate- 

 ly. Posterior and lateral extent of mesodermal poten- 

 cies has not been specified. 



From Rudnlck igl^lj-: Quart. Rev. Biol. 19:18? 



