( 175 ) 



While in another case a primördium was noticed which genetically 



belonged to the original spongy parenchyma I found in a small knob 

 which was still covered by an intact epiderm, and did not rise more 

 than 85 jz above its surroundings, and in this case had been formed 

 by special proliferation of the palissade parenchym, a distinct young 

 meristem immediately below the epiderm. The epiderm cells themselves 

 however, did not take part in t/te formation of the meristem. 



In a word, meristem formation may take place as well by cells, 

 descending from the spongy parenchyma and the subpalissade cells, 

 as from such as have been formed by hyperplasia of the palissade 

 parenchyma, the epiderm, however, plays no part. In other words: 

 the adventitious buds on the leaves of Gnetum Gnemon are endogenic 

 formations. 



In the beginning the young meristem increases in si7.e by its own 

 active growth as well as by new cells from the immediate vicinity 

 becoming meristematic. 



When the meristem has reached certain dimensions, it partly 

 becomes loose from the surrounding tissue. This is brought about 

 by some of the cells, forming the transition between the meristem 

 and the surrounding tissue, being dissolved and resorbed. 



This dissolution process proceeds along the whole upper side of 

 the meristem, so that the growing point of the adventive bud comes 

 to be placed in a slit-shaped space. 



The greater the depth at which the meristem was originally formed 

 inside the knob, the thicker is the layer of tissue which ultimately 

 separates the bud from the outer world and the further the develop- 

 ment within the enclosure proceeds. This explains how it is possible 

 that knobs, no larger than 1 millimetre, open, while much larger 

 ones remain persistently closed. 



The appearance of two meristems within the same knob is a very 

 common occurrence; once I found as many as four meristems in 

 one knob. 



The buds assume a green colour while they are still entirely 

 enclosed within the knob and hence must have the power, like the 

 germinating plants of Ephedra and the Coniferae, to form chlorophyl 

 independent of light. 



The sprouts growing out of the adventitious buds always remain 

 short and tender. The biggest I observed reached a height of about 

 3,5 centimetres and consisted of a stem with 5 internodes (including 

 the basal part) of which the upper one reached the greatest length 

 [almost 2 centimetres), while the leaflets on the last node became 



12 



Proceedings Royal Acad. Amsterdam. Vol. X. 



