81 



is usually stopped by excess of carbon dioxide 1 but 

 Josing 2 reports that streaming can continue in the pres- 

 ence of carbon dioxide if the cell is illuminated. Sever- 

 al investigators have observed a detrimental effect of ^ 

 carbon dioxide on germination and a tendency for it to 

 produce or lengthen the dormancy of seeds. Similarly, 

 Lopriore 4 has observed interference with the development 



T. Kuhne,- Unters. uber das Protoplasma p. 164 

 (1864); Demoor,- Arch. Biol. 15: 190 (1893); Loproire,- 

 Jahrb. wiss. Bot. Z8: 531-626 (1895); KLenm,- Jahrb. wiss. 

 Bot. 28: 636 (1895); Samassa,- Verh. naturh. Ver. Heidel- 

 berg 6_: (1898); Swart,- Protoplasmic streaming, p. 



78 (1903). 



2. Jahrb. wiss. Bot. 36: 19 7 (1901). 



3. See especially Kidd,- Proc. Hoy. Soc, (B) 

 7: 408-421, 609-625 (1914); also: Bernard,- Lecon sur 



les effets des substances toxiques, p. 200 (1883); Ifengin, 

 G. H. 122 : 747-749 (18y6); Marcacci,- Arch. ital. 3iol. 

 19: 140 (1892). Xidd reports, hov/ever, that low partial 

 pressures of carbon dioxide may stimulate germination 

 ( loc . cit .. pp. 60y-625). This is perhaps a case of the 

 apparently general rule that low concentrations of poi- 

 sonous substances are stimulating, see Preeand Trelease,- 

 Johns Hopkins Univ. Girc. : (1917). 



4. Jahrb. wiss. Bot. 28: 531-626 (1895). 



