292 



THE AMERICAN NATURALIST [Vol. XLVII 



period of several months' rest. The stage of maturity 

 and the parts burned of each bud were not recorded and 

 therefore the condition and exact treatment of this par- 

 ticular bud are unknown. 



As a check on the uncovered decapitated pistils, 5 pollen 

 from the same and other varieties was applied directly 

 to the cut surface of the styles ; in addition to pollen, cane- 

 sugar solutions varying from 25 per cent, to 50 per cent, 

 in strength, 6 stigmatic fluids, and in one instance nectar 

 taken from the base of buds, were also applied. If the 

 shortened pistils could be fertilized, it was thought that 

 certain impossible crosses, as N. alata X N. Forgetiana 

 and Mirabilis Jalapa X M. longiflora might be made, 

 providing the difficulty existed in the extreme length of 

 the styles. In one case, the applied stigmatic fluid and 

 the pollen grains were taken from the same species. This 

 precaution was used, as it was thought that the stigmatic 

 fluid of one species might contain an enzyme or an in- 

 hibiting substance which would prevent the germination 

 of foreign pollen grains. This supposition was sup- 

 ported by the growth of pollen grains in stigmatic fluids 

 placed within Van Tieghem cells. For instance, the 

 N. glauca pollen grains germinated and made good 

 growth in the stigmatic fluid taken from N. glauca plants, 

 while N. suaveolens pollen grains did not extend their 

 pollen tubes in the stigmatic fluid taken from N. For- 

 getiana. If the tissue of the style contains an inhibiting 

 agent, also, the germination of pollen grains on the cut 

 style would be of no benefit. (This supposition may ex- 

 plain the negative results. 7 ) 



•Ewert (1909) quotes Gartner who states that Henschel obtained seven 

 ripe fertile seed from six blossoms of Salvia sclarea whose pistils had been 

 destroyed, and four abortive seeds from three capsules of Polenu i 

 gracile whose pistils had also been destroyed. 



•A 33 : \ per cent, strength was u^l in the later work, as the poll. 



T The presence of one or more inhibiting agents might be used to explain 

 the failure of grafts between plant species, for they may act like the : 

 bodies, produced in animals by the transference of the blood of one sp< 



