166 



As long as the stem is still under tlie ground, its top is 

 sharply bent downward and the still perfectly closed flo- 

 wer is protected by the three leaves, still yellow then, by 

 which it is enveloped, and hangs down. As soon as the, 

 top of the stem has come above the ground and also the 

 flower has come free, this latter raises and soon imfolds 

 itself; then the basai collar spreads out and turns green. 

 The measurements of growth were made in the stage 

 between the period when the stem is not yet visible above 

 the ground and that, in which, after the petals and stamens 

 hâve fallen ofF, only the fertilised pistils remain. About 

 this time the longitudinal growth stops. Whether after- 

 wards, during the ripening of the fruits, a new period of 

 growth begins, as in other plants, I hâve not investigatcd. 



The plants, serving for the investigation, were placed 

 in a hothouse of the Botanical Garden at Amsterdam, in 

 which the mean température was 20" C. and in which 

 the spécimens developed very rapidly and entirely normally. 



I will first show by a few examplas that the présence 

 of the organs on the top is necessary in order to cause 

 the stem to grow normally in length. 



The stem of an Eranthis was on February 4, 1905, 40 mm. 

 long, measured from the base near the rhizoma to the 

 junction of the leaf-whorl. Placed in the hothouse the 

 plant was at first measured daily, afterwards every other 

 day; for briefness' sake I shall hère only give the length 

 reached by the stem after every four or fivo days. 



In the same time the development of a stem on which 

 leaves and flower had been eut away, was: 



