Botany. — "7%^ disapfearance of the diploid and triploid magni- 

 coronate narcissi from the larger cultures and the appearance 

 in their place of tetraploid forms". Bj Dr. W. E. dk Moi,. 

 (Communicated by Prof. G. van Iterson Jr.). 



(Communicated at the meeting of June 24, 1922). 



I. Introduction. 



Simultaneously witii my investigations into the causes which lead 

 to the immense variety of size and form in the Hj/acinthus orienialis 

 in Holland, I commenced a similar research with respect to the 

 species of narcissi and narcissus-hybrids under cultivation. These 

 comparative researches have led to some noteworthy results. One 

 conclusion I arrived at was that, as is the case with Hyacinthus 

 orientalis, the remarkable size of the bulbs, leaves and flowers which 

 characterize the bastards oï Narcissus Pseudonarcissus now (lv\\\^\'2^.%é, 

 correspond mainly with the number of chromosomes of which,- 

 according to my cytological observations,, the somatic nuclei consist. 



This feature which, as far as I have been able to observe, occurs 

 in Hyacinthus orientalis only in the Dutch cultures, is found both 

 in England and in the Netherlands in Narcissus Pseudonarcissus, 

 and is more pronounced than in the hyacinth. In the latter there 

 are probably no tetraploid plants yet, whereas there are several in 

 the Narcissus Pseudonarcissus. 



II. Some results of the cytological investigation. 



The preparations which I used in my cytological researches were 

 made in the same way as those for hyacinths. The thickness of the 

 sections is 10 or 15 n accoiding to the size of the cells and nuclei. 



AscHERSON and Graebner (1) give the Magnicoronati as the 1^^- 

 section of the sub-genus Eunarcissus. This section is entirely formed 

 by the class i\^. Pseudonarcissus, which they divide into 2 sub- 

 classes, N. festalis and N. minor. For convenience sake in describing 

 the varieties studied, I shall keep to this classification, except that 

 I shall place the sub-division N. minor first. 



1. N. minor. 



The somatic nuclei of N. minor (the type), N. nanus, N . minimus 

 and N. cyclamineus (which is best classed with the sul)-species 



