PHYSIOLOGICAL CHARACTERISTICS OF AXIATE PATTERNS 155 



times that of ventral, ammonia production higher dorsally, and Httle or no 

 aerobic glycolysis in any part.-^' It is not evident that the very small frag- 

 ments used in these determinations contribute in any way to greater 

 accuracy or certainty of results. If metabolism is altered by isolation, 

 greater alteration may be expected with smaller than with larger pieces; 

 in isolated pieces of planarians and hydroids such differences appear. The 

 data do not indicate whether isolation alters metabolism in these embry- 

 onic pieces or whether size of piece may be a factor in rate after isolation. 



According to another series of determinations of oxygen uptake, ^^ that 

 of the apical half of the blastula is 3.1 times that of the basal half, that 

 of the dorsal inductor region twice that of the intact gastrula, that of the 

 neural plate of the neural stage 2.61 times that of the whole neurula, and 

 that of the anterior region of the later embryo higher than that of the 

 posterior part. 



In a later paper J. Brachet (1939) finds little difference in oxygen up- 

 take between dorsal and ventral sides in R. fusca at the beginning of 

 gastrulation and agrees with Boell, Needham, et al. that the great dififer- 

 ence found earlier probably resulted from the presence of two cell layers 

 in the dorsal region; that is, the determinations on single embryos required 

 so much time and temperature was so high that invagination was ad- 

 vanced before they were completed. However, it is perhaps still a ques- 

 tion whether the second cell layer beneath some part of the dorsal ecto- 

 derm would increase oxygen uptake 47 per cent. There is also the possi- 

 bility the oxygen uptake increases in the invaginated portion of the dorsal 

 region. Brachet's later determinations of CO, production by a colori- 

 metric method show the dorsal side 29 per cent higher than the ventral; 

 but this difference is, at least in part, due to the difference in respiratory 

 quotient. He also finds dorsal pieces more susceptible than ventral to 

 agents which inhibit glycolysis (monoiodoacetate and NaF). Carbohy- 

 drate metabolism, indicated for the dorsal region by the respiratory quo- 

 tient about unity, he regards as not essential to induction, and he shows 

 that induction is not necessarily prevented by inhibition of glycolysis. 



^3 Needham and Boell, 1938; Boell, 1938; Boell, Needham, and Rogers, 1939; Boell and 

 Needham, 1939; Boell, Koch, and Needham, 1939; Needham, Rogers, and Shih-Chang Shen, 

 1939. More recently Boell and Nicholas (1940, Absir. Amer. Soc. ZooL, Anal. Bee, 78, 4, 

 Suppl.) have found a basipetal decrease in respiration dorsally and a steeper decrease ven- 

 trally, but they maintain that when corrections are made for the different amounts of yolk 

 in the different regions actual quantitative respiratory differences do not appear. See also 

 Needham, 1939, "Biochemical aspects of organizer's phenomena," Groidh, Suppl. 



" Fischer und Hartwig, 1938; oxygen as mm^O, per 10 mg. dry weight per hour. 



