1903] CURRENT LITERATURE 477 
experimental methods. Field studies showed that the stamens vary from o 
to 13, forming a bimodal curve with principal maximum on 3 and secondary 
maximum on 5. The relative prominence of the maxima, the value of the 
mean, and the coefficient of variability depend upon habitat and time at 
which collections are made. Although in nature the curve was always 
bimodal, three of the cultures produced asymmetrical monomodal curves 
which agreed with Pearson’s theoretical type IV, in one instance the asym- 
metry being so slight as to give essentially the Gaussian probable error curve. 
This reduction to a homogeneous condition is an unusual result where the 
homotyposis of organs which have their origin in relation to the phyllotactic 
spiralis involved. The maximum on 5 was found to be completely eliminated 
in the third generation of plants grown in diffused light, while that on 3 was 
eliminated by the high manuring of plants which had been observed to have 
already a strong development of the higher mode. By still higher manuring 
he secured a curve with a strong maximum on 5 and a slight one on 8, show- 
ing thus by the maxima on 3, 5, 8, a perfect agreement with the Schimper- 
Braun series. Of the external factors light intensity was found to be the 
most important, and the richness of the soil in available foods next. 
Finally it was found that in all cases the modal condition changes as the 
flowering season advances, the number of stamens beginning low, reaching 
its maximum only after some time, and falling again near the end of the 
season. This contravenes Burkill’s?? conclusions, which rest upon occasional 
collections aggregating less than 400 flowers cultivated in pots in a tropical 
greenhouse, while Reindhl has observed 44,542 flowers, including in the case 
of cultures all the flowers produced during the flowering season. It also 
is not reached until some time after the flowers begin to bloom, while in Aster 
Prenanthoides the maximum vegetative activity precedes the development 
of the flowers,—G. H. SHULL. 
. HEINRICHER’S studies of the green half-parasites** have advanced 
tniisidecably the boundaries of our knowledge. It was to have been expected 
that a group like the Rhinanthaceae, apparently half way on the road to 
holoparasitism, would yield results of surpassing interest. In his earlier 
paper Heinricher presents studies on Odontites Odontites, Euphrasia stricta, 
and Orthantha lutea. He finds that germination is independent of host 
stimuli, but that haustoria require a host stimulus in order to induce develop- 
ment. Odontites was brought to a state of flower and fruit entirely without 
parasitic nutrition, while Euphrasia could nourish itself toa much less degree- 
?23BURKILL, On some variations in the number of stamens and carpels. Jour. 
Linn. Soc. Bot. 31 : 220 e¢ se 5 
SHULL, G. H., Amer. Naturalist 36: 111-152. 1902. 
3! HEINRICHER, EMIL, Die Griinen Halbschmarotzer. Jahrb. Wiss. Bot. 31: 
77-124. 1898; 32: 389-452. 1898; 36: 665-752. 1901; 37: 264-337. 1902. 
