Morphologie, Teratologie, Befruchtung, Cytologie. 221 



has 36 (?), while C. arcticurn L., has 45 chromosomes. It is a note- 

 worthy fact, that the numbers 18, 27, 36 and 45 are all multiples 

 of 9. The sizes of the chromosomes of these plants are also diffe- 

 rent. Generali}'' speaking, the size of the chromosomes is inversely 

 proportional to the number of the chromosomes. The sizes of the 

 chromosomes of different plants with the same number of chromo- 

 somes however, are not always the same; for example the chromo- 

 somes of C. nipponicum, C. carinatum, and C. coronarium are larger 

 than those of C. japonicum, C. lavandulaefolium and C. Marschallii. 



The meiotic nuclear division was studied in the pollen mother- 

 cells of C. coronarium. In the earliest stage the parallel arrange- 

 ment of the nuclear thread is clearly visible, but this becomes 

 obscure gradually in the subsequent stages. The longitudinal Split- 

 ting of the nuclear thread occurs in the later synapsis. So in this 

 stage, the parallel arrangement and the Splitting are both visible. 

 In the second contraction stage, the continuous Single spirem thread 

 Segments into 9 looped or ring-shaped portions; thus in the spirem 

 stage the chromosomes are arranged end to end, not side by side. 

 According to the different authors, the explanations of the parallel 

 threads in the meiotic prophase are different. Somfe authors regard 

 them as the parallel arrangement of the whole chromosomes, while 

 others take them for the longitudinal Splittings of the chromosomes 

 themselves. The case in C. conorarimn affords a good explanation 

 for both Views; for in this plant ihe parallel arrangement and lon- 

 gitudinal Splitting can be seen at the same moment of the meiotic 

 prophase. 



The type of the tetrad division of the pollen mother cell of 

 Chrysanthemum is quite noteworthy. At the end of the meiotic 

 nuclear division, the new partition cell-walls appear in the form of 

 protuberances in the inner surface of the cell-wall of the pollen 

 mother cells. These protuberances proceed centripetally and con- 

 strict the pollen mothercell into four equal portions. This type of 

 tetrad divisions reminds us of the type of tetrad division of the 

 tetraspore mothercell in Rhodophyceae. 



The several embryosacmothercells in the same ovule were 

 reported already by many authors in many Angiosperms. Chrysan- 

 themum presents, however, a very conspicuous exemple in this 

 respect. C. nipponicum and C. Decaisneanum have only one embryo- 

 sacmothercell in each ovule. But in other Chrysanthemums two 

 or more embryosacmothercells are found almost always in the same 

 ovule; especiaily in C. Marschallii we met with five to ten embryo- 

 sacmothercells in one and the same ovule. The meiosis of these 

 cells goes normally without any indication of disintegration. 



M. J. Sirks (Haarlem). 



Wagner, R., Ueber Ableitung einiger Blütenstände. 



(Verh. Ges. deutscher Naturf. u. Aerzte. 85. Vers. Wien. IL 1. 



p. 674-676. Leipzig, F. C. W. Vogel. 1914.) 



Die eigenen Studien des Verf. bringen wesentliche Veränderun- 

 gen der herrschenden Ansichten. 



1. Aus dem Pleiochasium sind alle bisher analysierbaren Inflo- 

 reszenzen abzuleiten 



2. Bei den Pleiochasien verarmen die Partialinfloreszenzen I. 

 Ordnung in akropetaler Folge; der nämliche Prozess spielt sich in 

 den Teilblütenständen höherer Ordnung ab, bis schliesslich nur 



