:;70 si mmakv ot 01 kkknt reseakches delating to 



BOTANY. 



GENERAL, 



Including the Anatomy and Physiology of Seed Plants. 



Cytology, 

 Including- Cell-Contents. 



Chromosome-reduction in Oenothera.* — R. R. Gates publishes 

 brief review of the work of B. M. Davis on CEnoth&ra grand/flora. After 

 reference to tbe importance of the latter work in confirming two funda- 

 mental points, viz. the absence of pairing of separate threads during 

 synapsis, and the subsequent end-to-end pairing (telosynapsis), the 

 reviewer points out the differences in the account of reduction in 

 0. grandiflora and in 0. LamarcMana. The first difference, viz. the 

 existence of prochromosomes, is regarded as insufficiently proved, but 

 the description of the heterotypic chromosomes is regarded as showing a 

 greater attraction of the individual chromosomes to pair than is found 

 in 0. Lamarckiana. This may possibly be connected with the mutation 

 of the latter. 



Chromosomes of (Enothera Mutants and Hybrids. t — R. R. Gates 

 publishes a brief summary of his work dealing with the cytology of 

 (Enothera. The experiments were begun in 1905, and up to tbe present 

 time have yielded the following results : In 0. Lamarckiana the number 

 of chromosomes is fourteen, the reduced number being seven. "When 

 tli is species is crossed with 0. lata the number of chromosomes found 

 is twenty, with ten as the reduced number, but a subsequent cross 

 gave the same number as in 0. Lamarckiana. In telophase the chromo- 

 somes of the heterotypic mitosis look like tetrads but appear to be really 

 bivalent. In 0. rubrinervis the chromosomes number fourteen and are 

 of the usual size, although the pollen-mother-cells are large and have 

 protoplasmic connexions. In 0. nanella the chromosomes are also 

 fourteen in number. In 0. biennis crueiata (a mutant of 0. Lamarckiana) 

 in the synapsis of the pollen-mother-cells there is an additional body 

 resembling a small nucleolus, but it persists after the latter has Woken 

 down. This is probably the same body as is seen at the side of the 

 spindle in both 0. lata and 0. Lamarckiana, also in hybrids between 

 0. lata and 0. Lamarckiana and in 0. rubrinervis. These bodies may 

 be termed heterochromosomes provisionally, but their full history and 

 origin are unknown. The writer hopes to publish further results before 

 long. 



* Bot, Gaz., xiix. (1910) pp. 65-6. 



+ Advance print from Proc. 7th Internat. Zool. Congress, Boston, 1907 (1910) 

 pp. 1-4. 



