54 Varietäten, Descendenz, Hybriden. 



assembled under binomials, X Q- palaeolithicola {ellipsoidalis X 

 velutina) and X ö- Schmettei (btcolor X ynacrocarpa) are made 

 known for the first time, and the following names are given to 

 recorded hybrids either unnamed or under preoccupied names: 

 X Q- Ashei {Catesbaei X cinerea), X Q- Beadlei {alba X Michauxn), 

 X Q- bliifftonensis {Catesbaei X falcata), X Q- caduca {cinerea X 

 nigra) , X Q- carolinensis {cinerea X marilandicä) , X Q- Deami {alba 

 X Muehlenbergii) , X Q- exacta (imbricaria X palustris) , X ö- 

 Taxoni {alba X prinordes), X <?■ Fernowi {alba X stellata), X jQ. 

 Giffordi {ilicifolia X Phellos), X ö- ^^/^« {macrocarpa X Muehlen- 

 bergii), X ö- Mellichampi {Catesbaei X laurifolia), Q. organensis 

 {arisonica X grisea), X ö- podophylla (X iß- petiolaris Ash.^ , z:^ cine- 

 rea X '^velutina), X ß- Pateri {rubra} X velutina), X ö- Rehderi 

 {ilicifolia X velutina), X ö- Robbinsii {coccinea X ilicifolia), X ß- 

 Smallii {georgiana X niarilandica) , X iö- sterilis {marilandicä X 

 nigra), X jQ. subfalcata (X Q- falcata Ashe, =:^ falcata X Phellos), 

 X Q- subintegra {cinerea y^ falcata), X Q- sublaurifolia {cinerea X 

 laurifolia), and X Q- Sudworthi {falcata X velutina). Trelease. 



Winge, Ö., The Chromosoraes. Their numbers and gene- 



ral importance. (Compt. rend trav. Lab. Carlsberg. XIII. p. 



131—275. 46 Text-Fig. 1917.) — Also in Danish: Studier over 



Planterigets Chromosomtal og Chromosomernes Be- 



tydning. (Medd. Carlsberg Lab. XIII. p. 127-267. 1917.) 



The Contents are divided in 8 chapters: 1. General observations 



on the alternation of generations and nuclear morphology. 2. The 



System of chromosome values in the vegetable kingdom. 3. Some 



new chromosome numbers. 4. Theoretical studies on the origin of 



the System of chromosome numbers. 5. Heterochromosomes. 6. The 



persistency of chromosomes, and their hereditary significance. 7. Chro- 



mosomes in hybrid organisms. 8. Hyperchromatic cells. — Finally 



a summary and a list of literature, containing 184 titles. 



The work is a result of genetic experiments and cytological 

 investigations on plants, and parallels are drawn to the results of 

 zoological investigators. — It is not possible to give a thorough 

 report, but the summary is here reprinted: 



As the "cell" in several, especially primitive, organisms, e. g. 

 amoeba, is withotit walls, and wall formation to be regarded as a 

 morphologically and physiologically higher stage, which is in several 

 plants connected with division of function, so also all would seem 

 to indicate that the nucleus is of phylogenetically younger origin 

 than the living cell itself, and that it indicates a physiologically 

 greater differentiation v^ithin the same. — In lower organisms, 

 such as for instance Plasmodiophoraceae and Entorrhisa, the chro- 

 matin is not inseparably connected with the nucleus. In Entorrhisa, 

 we even find in the spores a nucleus entirely free from chromatin, 

 and free, split chromosome-like bodies in the cytoplasm. 



A Statistical survey of the haploid chromosome numbers in 

 higher plants shows that the chromosome numbers can as a rule be 

 resolved into the prime factors 2 and 3. More rarely, 5 and 7 

 appear as factors. From what is known, 8 and 12 must be regarded 

 as the most frequently occurring chromosome numbers, and are 

 far more offen met with than the remainder: next in order come 

 16, and thereafter 6 and 9. 



In the case of higher plants it is a rule that the species in a 



