26o The Plant World. 



spite of the presence of the alleged "defenders," in short 

 that the whole familiar story of destruction by leaf-cutting 

 ants and protection by other species is to be held as un- 

 proven. As Schimper is no longer with us his critic seems 

 for the present to have the field to himself. 



Kinzel reports that in h's experiments with seeds of 

 Nigella saliva germination failed to take place in light at 

 a temperature of 20 degrees (Centigrade?), while in dark- 

 ness at the same temperature 94 per cent, of the seeds sprout- 

 ed. At 10 degrees and ev'en 15 degrees germination in light 

 took place, though slowly. Seeds of Poa pratensis kept at 

 a temperature of 20 degrees failed altogether in darkness, 

 while in light 95 per cent, germinated. 



Arcangeli reports that Euryalc fcrox and Victoria regia 

 are physiologically heterospermous, that is seeds of the same 

 fruit germinate at different successive periods. He suggests 

 that this habit tends to the preservation of the species, and 

 that it may occur not only in the seeds of Bowering plants, 

 but also the spores of cryptogams and even in pollen grains. 



PVanceschini in a recent paper enumerates 628 species 

 belonging to 62 families of flowering plants which exhibit 

 some form of cleistogamy. Reviewing the various theories 

 as to its origin, the author concludes that cleistogamy is not 

 a result of mutation, but is a variation induced by external 

 agencies which has gradually become permanent. Tuzson, who 

 has investigated the same subject, has observ^ed two individ- 

 uals of Robinia pseiidacacia which produced only cleistoga- 

 mous flowers. He is disposed to refer the cause in this case 

 to unusually early maturing of the sexual cells. 



