ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 
93 
Development of Primary Sieve-Tubes.* — M. G. Chauveaud defines 
what he terms “ the phase of maximum differentiation ” in the develop- 
ment of sieve-tubes. When the tube begins to lengthen, the lateral 
walls become thicker inwardly, but the thickening is not uniform ; elon- 
gated punctations appearing in them, and at the same time rounded 
punctations on the transverse walls, these becoming ultimately the pores 
of the sieve. This is the period of maximum differentiation; subse- 
quently, as the tube elongates, the sieve-structures become thicker, but 
the pores less and less distinct. 
Development of the Phloem-Elements in Vascular Bundles.^ — 
M. L. J. Leger describes the occurrence in young procambial bundles of 
“pearly” cells, distinguished by their thick white refringent longi- 
tudinal walls, which are shown, by their chemical reactions, to be com- 
posed of cellulose. They are first formed, at the expense of the cambial 
or procambial cells, in the outermost layers of the bundle, the formation 
gradually advancing inwardly. Subsequently these “ pearly ” cells either 
disappear altogether, or revert to the condition of ordinary parenchy- 
matous cells. 
Vascular Bundles in the Pith of Alnus.J — In the pith of an example 
of the black alder, Alnus glutinosa, Herr T. Kiinkele finds bundles within 
the pith and entirely proper to it, without any union with the normal 
vascular bundles. The vessels (or tracheids) have thickened lignified 
strongly refractive walls, often with bordered pits. The author regards 
them as probably survivals of normal bundles which have originated in 
the pith. 
Rudimentary Silicified Cystoliths in the Loranthace8e.§ — Herr F. 
Kolpin-Ravn finds that the so-called “ mucilage-cell-spheres ” found in 
various Loranthacese ( Viscum album and articulatum , Loranthus europseus , 
Phorodendron rubrum and emarginatum) have been inaccurately described, 
the cell-walls not responding to the reactions for mucilage. He asserts, 
on the other hand, that they show the reactions for silica, and compares 
them to the rudimentary cystoliths in the Borragineae, Composite, 
and Cucurbitaceae. They differ, however, from the structures in these 
orders in containing no calcium carbonate. 
Anatomy of Solanace3e.|| — According to Herr F. Fedde, the Sola- 
naceae present a number of characters which differentiate them sharply 
from all allied orders, while it is very difficult to separate the families 
from one another by anatomical characters. The epiderm always con- 
sists of only a single layer, it is not lignified, and the cuticle is always 
thin. There is always a layer of collenchyme in the herbaceous parts of 
the stem. The vascular bundles are always collateral ; they have never 
a protecting sheath. The vessels of the secondary xylem and the 
tracheids have bordered pits. In most of the genera there are very 
minute crystals ( Krystallsand ) in the cortical and medullary parenchyme 
and in the leptome. When these are wanting, there are larger crystals 
* Comptes Eendus, cxxv. (1897) pp. 546-7. f Tom. cit., pp. 619-20. 
t Bot. Centralbl., lxxii. (1897) pp. 1-6 (1 pi.). 
§ Bot. Tidskr., xxi. (1897) pp. 53-8 (with figs.). See Bot. Centralbl. lxxii 
(1897) p. 273. ’ 
II Beitr. z. vergleich. Anat. d. Solanaceen, Breslau, 1896, 48 dd See Bot 
Centralbl., lxxii. (1897) p. 144. 
