ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 
319 
Internal Phloem in Gelsemium sempervirens.* — Miss Caroline 
Thompson states that the internal phloem in this plant originates as four 
longitudinal tracts in the primary meristem, and steadily increases until, 
by the eighth or tenth year, it has entirely destroyed the pith. In the 
petiole a bicollateral bundle arrangement exists at the base; but this 
quickly changes to the ordinary collateral relation by the passage of the 
internal phloem through the xylem. Each bundle, in passing out into 
the petiole, subdivides into three parts, two of which remain in the stem 
and soon come together again, while the third passes out through the 
xylem. From the second year onward, the internal phloem patches of 
the stem show areas of crushed and obliterated tissue where the previ- 
ously formed phloem had been pushed inwards by the younger elements. 
In older stems eight large phloem patches, formed by division of the 
original four, entirely fill up the pith area. 
Anatomy of the Hippomanese.f — Herr H. Herbert describes in de- 
tail the anatomy of the stem and leaf of this tribe of the Euphorbiaceae. 
The most widely distributed secreting elements are unseptated latex- 
tubes ; septated latex-tubes occur only in Manihot. The stomatal appa- 
ratus is greatly developed, there being almost always subsidiary cells as 
well as guard-cells. Stinging hairs occur in Jatropha urens. 
(40 Structure of Org-ans. 
Biology and Morphology of Pollen.J — Prof. A. Hansgirg sums up 
his observations on various points connected with the emission of pollen- 
tubes, the protection of pollen-grains from rain, and the length of time 
during which the grains may remain functional. The variations depend 
on the vital conditions of the species rather than on any genetic relation- 
ship. The characters in the points named, and in the concealment or 
exposure of the sexual organs, are noted, from the author’s personal 
observations, in the case of a very large number of species belonging to 
all the more important natural orders ; and the following classification 
is propounded, dependent on these characters : — (A) Plants whose pollen 
is resistant to moisture, and germinates in pure water. ( a ) Species in 
which the sexual organs are more or less protected against rain, &c. ; 
(&) Species in which the sexual organs are only slightly or not at all 
protected against atmospheric precipitation. (B) Plants whose pollen 
is not resistant to moisture, and does not germinate, or only very imper- 
fectly, in pure water ; (a) Species in which the sexual organs are com- 
pletely or partially protected against rain, &c. ; (b) Species in which 
the sexual organs are only slightly or not at all protected against rain, 
usually completely exposed. 
Capsular Fruits.§— Herr A. Weberbauer gives an exhaustive treatise 
on the anatomy and physiology of capsular fruits, which he classifies 
under three groups, viz. : — (A) Capsules splitting by longitudinal fissures, 
* Bot. Gazette, xxv. (1898) p. 118. 
t ‘ Anat. Untere. v. Blatt u. Axe d. Hippomaneen,' 62 pp., Miinchen, 1897. See 
Bot. Centralbl., lxxiii. (1898) p. 49. 
t SB. K. Bohm. Gesell. Wiss., 1897, No. xxiii. (76 pp.). Cf. this Journal, 1897, 
p. 310. 
§ Bot. Centralbl., lxxiii. (1898) pp. 54-9, 97-104, 135-42, 161-8, 193-202, 250-7, 
296-302 (2 pis.). 
1898 
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