306 MEMOIRS OF THE NEW YORK BOTANICAL GARDEN. 



Baranetzky therefore, that the periodicity of growth maintained by a 

 plant after it has been deprived of illumination, is an after-effect, 

 and which supported by Vines seems well defended, to whatever this 

 daily periodicity may be due. Furthermore, it might be expected 

 an organ would carry on growth with a rh3'^thm due to the action of 

 factors concerned with an extremely early stage of its existence. It is 

 probable that the behavior of any single species however, may not be 

 safely predicted. Thus the auxanometric measurements of Arisaema 

 trifhyllmn disclose a rhythmic action, quite as well marked as that 

 of the normal plant, when grown in a dark room at constant tem- 

 peratures (pp. 68-70). 



The measurements of a leaf of ^lamasia during a continuous 

 period of fifty days in a dark room at a constant temperature (p. 86) 

 gave opportunity for observations of growth under conditions in which 

 the food-supply, moisture, temperature and darkness were practically 

 uniform. A consideration of the facts shown in the curve plotted 

 from the auxanometric data brings to light the fact that the variations 

 in this instance were exceedingly irregular, and seemingly subject to 

 no rule of any kind. No control observations were made on this 

 species for the purpose of obtaining the variations in normally grown 

 plants. The variations of Arisaema, on the other hand, were fairly 

 parallel to those of the specimens under normal alternations of 

 daylight and darkness with the temperature fluctuating. 



The observations described in this memoir, together with the 

 records of previous investigations upon etiolation demonstrate most 

 conclusively that the growth of the aerial organs of green seed plants 

 in darkness is not accompanied by the usual degree of differentiation 

 of the several tissues. The amount of growth, or increase in volume, 

 that may be accomplished by the shoot by the extension of the im- 

 perfectly developed tissues in the absence of illumination is subject 

 to great variation. In many species the total length, diameter and 

 volume of the etiolated shoot, and its various members is not so great 

 as in the normal, and the rate of growth may not be so rapid as in 

 the normal. The buds and seeds of a number of species, and also 

 the spores of many pteridophytes will not awaken from a resting 

 condition and begin the growth leading to the development of the 

 shoot except under the influence of light. On the other hand, some 

 species of the higher plants, as well as some of the lower forms, 

 carry on the growth of the main axis at an accelerated rate in dark- 



