ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 
611 
BOTANY. 
A. GENERAL, including the Anatomy and Physiology 
of the Phanerogamia. 
a. Anatomy. 
(1) Cell-Structure and Protoplasm. 
Possible Function of the Nucleole in Heredity.* — Dr. H. H. Dixon 
offers a suggestion, founded on recent observations respecting the be- 
haviour and development of the nucleus and of its constituent elements. 
It is that, “ during the resting stage of the nucleus, the hereditary sub- 
stance is distributed between the chromatin-threads and the nucleoles. 
This distribution is so arranged that the units of hereditary substance, 
idioblasts (Hertwig) or pangens (de Vries), which determine the attributes 
of the cell in which the nucleus is actually situated, are located in the 
chromatin-thread, while the inactive or dormant idioblasts are contained 
in the nucleole or nucleoles.” 
Reduction of Chromosomes.! — Prof. G. F. Atkinson describes two 
cases of this phenomenon which present important divergences from all 
the vegetable types hitherto known. 
(1) Arissema iriphyllum (Araceae). The process was followed out 
in detail in the formation of the pollen-mother-cells. The special pecu- 
liarity is that, while longitudinal division precedes transverse division of 
the chromosome, both divisions occur during the first or heterotypic 
division, and the real reduction follows soon after the pseudo-reduction 
in the heterotypic division. This has not previously been observed in 
plants. 
(2) Trillium grandijlorum (Liliacese). In the same process the chro- 
mosomes retain their individuality through the daughter-nuclei from the 
anaphase of the first division to the prophase of the second division. 
There is no evidence of a longitudinal division during the daughter- 
nucleus stage. 
(2) Other Cell-Contents (including- Secretions). 
Yellow Colouring Matters which accompany Chlorophyll.^ — Mr. 
C. A. Schunck finds, in all crude alcoholic extracts of healthy green 
leaves, two yellow colouring matters accompanying the chlorophyll — 
chrysophyll and xanthophyll ; this latter (the term being used in a 
somewhat restricted sense) being the predominant one, and identical 
with the principal yellow colouring matter of faded autumn leaves. 
Other yellow colouring matters may also be present. Chrysophyll and 
xanthophyll each give a characteristic absorption spectrum in the violet 
and ultra-violet region ; the former consists of three bands, the latter of 
four. Chlorophyll itself also gives three characteristic bands in the 
violet. Phyllocyaniu and phylloxanthin have bands in identical posi- 
tions with these three chlorophyll bands. 
* Ann. of Bot., xiii. (1899) pp. 269-78. 
t Bot. Gazette, xxviii. (1899) pp. 1-26 (6 pis.). 
X Proc. Roy. Soc., lxv. (1899) pp. 177-86 (1 pi.). 
