ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 
359 
BOTANY. 
A. GENERAL, including the Anatomy and Physiology 
of the Phanerogamia. 
a. Anatomy. 
(1) Cell-structure and Protoplasm. 
Protoplasmic Connection between adjacent Cells.* — Herr F. 
Kienitz-Gerloff enumerates a very large number of instances in which 
he has detected protoplasmic connection between adjacent cells : — Among 
Musci, all the cells of the stem of Thuidium delicatulum; among Filices, 
all the parenchymatous cells of the rhizome, the sieve-region of the 
vascular bundles, and the endoderm of Polypodium vulgare ; among 
Coniferae the bud-scales and cortex of Abies pectinata, the bud-scales of 
Pinus excelsa , the bud-scales and sieve-tubes of Pinus sylvestris ; among 
Angiosperms, the cortical cells of the rhizome, the embryo- and endo- 
sperm-cells, the young leaves, the central vascular bundle of the root, 
the fundamental tissue of the stem, collenchyme, epiderm, pith, cam- 
bium, mesophyll of the leaf, sclerenchyme, hairs, and other organs and 
tissues of plants belonging to a great number of natural orders of both 
Monocotyledons and Dicotyledons. 
These protoplasmic connections are not merely between cells be- 
longing to the same tissue ; they are even more common between 
adjacent cells belonging to entirely different tissues, as between epi- 
dermal cells and those of the cortex or collenchyme, and between the 
endoderm -cells and those of the primary parenchyme and of the vascular 
bundle in Polypodium vulgare. The author believes, in fact, that, in the 
higher plants, all the living portions of the entire plant are connected 
by threads of protoplasm. The perforation of sieve-tubes is simply an 
instance of this general law where the threads are of unusual thickness. 
In Phanerogams the thickness of these threads varies between 0 • 05 and 
1 • 0 /J, while in Thuidium delicatulum they were measured as thick as 3 /z. 
The thicker threads are usually solitary ; where they are thinner it is 
more common for a number to be collected together into a fusiform mass. 
In the opinion of the author no perforation of the cell-wall ever takes 
place ; but, at the spot where the threads pass through, no cellulose is 
formed at the time of cell-division. The connecting threads appear to 
be the remains of the spindle-fibres formed in the process of division of 
the nucleus. 
With respect to the physiological value of this protoplasmic con- 
nection, the author takes the view of those who regard the threads as 
the conducting path through which the protoplasm passes out of the 
vessels and sclerenchymatous fibres into the adjacent cells. 
A very complete bibliography of the subject is appended. 
Formation of Vacuoles t — Dr. G. Klebs contests the soundness of 
de Vries’ and Wont’s conclusion that vacuoles are in all cases formed 
by the division of others already in existence, a conclusion which 
has, he thinks, been in many cases arrived at by neglecting the evidence 
* Bot. Ztg., xlix. (1891) pp. 1-10, 17-26, 38-46, 49-60, 65-74 (2 pis.), 
t Op. cit., xlviii. (1890) pp. 549-59. Of. this Journal, ante , p. 58. 
