426 Ralph S. LiUie 



process, as well as those immediately induced by the latter. 

 Secondly, all of these changes appear to proceed best under con- 

 ditions of lack of oxygen^ — in other words, to be essentially anae- 

 robic in their nature. A predominance of anaerobic processes in 

 the changes mitiating development implies that an important 

 part is played here by reductions (in the chemical sense), since 

 anaerobic metabolism is always accompanied by the production 

 of strongly reducing substances. The possible part played by 

 such reductions in the processes of cell-division and growth has 

 been discussed by Mathews in the paper already cited; and the 

 above general result is therefore consistent with his view that the 

 production of asters (regarding this phenomenon as an essential 

 feature of mitosis) is the expression of localized reducing processes. 

 I can however hardly see my way clear to the conclusion that the 

 momentary elevation of temperature under anaerobic conditions 

 acts essentially by accelerating reductions and thus producing 

 astral areas. While this is a possible interpretation, it can, as almost 

 purely speculative, serve no particular purpose at present until 

 confirmed or disproved by experiment. Moreover, in the sea- 

 urchin egg the conditions seem of quite an opposite nature. Still, 

 so far as regards the main chemical conditions of the partheno- 

 genetic initiation of development in the starfish egg, the above 

 results appear to indicate very definitely a subordination of oxida- 

 tive processes to those of some other nature. 



This conclusion, while opposed to that reached by Loeb in the 

 case of the sea-urchin egg, is in harmony with the recent experi- 

 mental results of Delage^^ with the starfish. In this form partheno- 

 genetic development through the action of carbon dioxide was 

 found to be best obtained in the absence of oxygen; a high concen- 

 tration of oxygen in the carbon-dioxide-containing sea-water 

 proved definitely unfavorable; and, in general, the lower the pro- 

 portion of oxygen present, the better were the results obtained. 

 Thus the initiation of development through this means, as well as 

 through momentary warming, appears dependent on processes 

 of an essentially anaerobic nature. Precisely contrary relations 



^ Delage: Comptes rendus, vol. 145, p. 218, 1907. 



