398 
SUMMARY OF CURRENT RESEARCHES RELATING TO 
BOTANY. 
A. GENERAL, including the Anatomy and Physiology 
of the Phanerogamia. 
a. Anatomy. 
(1) Cell-structure and Protoplasm. 
Spermatogenesis in Lilium Martagon.* — Miss E. Sargant supple- 
ments her previous observations on this subject by a detailed account of 
the processes which take place in the nuclear divisions of the pollen- 
grain. They are strictly parallel to the corresponding stages in 
oogenesis. The first division of the pollen-mother-cell nucleus is similar 
in every detail to that of the primary embryo-sac nucleus, and may be 
termed heterotype ; the three later divisions are homotype. 
When the pollen-mother-cell is differentiated, its nucleus is built up 
of 24 chromosomes. The whole interval between the complete differen- 
tiation of the pollen-mother-cell and the formation of the young pollen- 
grains within it may conveniently be divided into four periods, viz. : — 
(1) The nucleus of the pollen-mother-cell grows larger and alters in 
structure, finally assuming the well-known spirem-condition ; (2) Twelve 
chromosomes are formed from the spirem- ribbon, and lie loose in the 
nuclear cavity; (3) The first karyokinesis of the pollen-mother-cell 
nucleus separates the two halves of each chromosome ; cell-division 
follows this nuclear division ; (4) The second karyokinesis divides the 
nucleus of each daughter-cell into two, and is followed by a correspond- 
ing cell-division. The various stages of these processes are described in 
great detail. 
The four nuclear divisions included in the spermatogenetic series of 
Lilium Martagon present one important characteristic in common with 
each other, with the three oogenetic divisions, and with ordinary vege- 
tative division. In each of these cases the effect of the whole process of 
karyokinesis is to divide each parent chromosome into a pair of daughter- 
chromosomes by longitudinal fission, and to build up duplicate daughter- 
nuclei from the duplicate sets of daughter-chromosomes thus formed.! 
Honeycomb Structure of Vegetable Substances.! — Herr K. Purie- 
witsch brings forward evidence in opposition to Biitschli’s theory of the 
honeycomb structure of protoplasm. In a large number of cases ex- 
amined by him — starch-grains of arrowroot, potato, and wheat, cotton- 
fibres, bast-fibres of Nerium Oleander, stone-cells of Podocarpus salicifolia, 
&c. — he found the structure to agree more with Nageli’s micellar theory 
than with Butschli’s. An argument against Biitschli’s theory is that if 
vegetable structures consisted of a meshwork containing fluid, they 
would present different optical properties when dry to what they do 
when moist, which does not appear to be the case. 
* Ann. Bot., xi. (1897) pp. 187-224 (2 pis.). Cf. this Journal, ante , p. 213. 
t The processes of fixing, imbedding, and staining employed by Miss Sargant 
will be found at p. 445. 
( X Ber. Deutsch Bot. Gesell., xv. (1897) pp. 239-47. 
