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: » _ This may be due to the loss of the Plasmodesmen, oF to i ju 
= i Bs, 14-15, : Igo. 
1902] CURRENT LITERATURE 79 
from early leaf conditions. The reductions in palisades, air spaces, bundles, 
and collenchyma are analogous to conditions in young leaves, or to leaves 
grown in the dark (though the reduction is more complete in the soil); but 
the entire loss of stomata, the great development of reserve foods, and the 
strong cutinization of the lower epidermis are without a parallel in other con- 
ditions than those furnished by a sojourn in the soil. In some cases, notori- 
ously in Lysimachia vulgaris, palisades appear in all conditions, even in leaf 
primordia while still in the bud and four or five centimeters below ground. 
The author consequently inclines to agree with Pick that palisades are due to 
hereditary influences, and that their direction only is determined by light. 
Thomas also thinks that the changes produced in soil conditions are in 
direct response to the new needs which arise there.— H. C. CowLES 
STRASBURGER,* in a very comprehensive paper, has taken up the whole 
subject of protoplasmic continuity in plant cells, He proposes the term 
Plasmodesmen for the connecting fibers. Among others, new observations 
are figured and described for Viscum, Pinus, Phytelephas, Nerium, the sieve 
tubes of Wistaria and Vitis, leaf cells of mosses, and the cells of grafts of 
Abies and Picea, But the paper is devoted fully as much to a critical 
résumé of the literature as to the recording of new observations. To reca- 
pitulate all the points made is plainly impossible in a brief review, and only 
a few of the most important will be mentioned. Kienitz Gerloff’s view that 
the Plasmodesmen do not originate in the fibers of the central spindle is con- 
firmed, and they must hence arise secondarily after cell division, but the 
question as to just how and when they are formed is left unsettled. Figures 
are given from Pinus and Wistaria confirming the prevalent belief that the 
thicker connecting strands of the sieve tubes originate as Plasmodesmen. As 
to the functions of Plasmodesmen, Strasburger confirms Gardiner's view, 
that in the endosperm of Tamus they serve to transport enzymes. In the 
medullary rays of Abies they may serve to transport proteids. That proto- 
P lasmic streams in general, however, pass through the fibers, or that they 
nels, for example, for the withdrawal of protoplasm from the leaves in the 
fall, 's shown to be entirely unproved. The importance of the P/asmodes- 
men for transmitting stimuli and for the normal development of organs is 
shown by a number of very interesting obser and exper Pr cee 
Plete plasmolysis results in the withdrawal of the Plasmodesmen from their — 
Pores in Mnium. Though when washed out the plasmolyzed cells again 
Press upon the cell walls, the Plasmodesmen are not reestablished, and the 
Plasmolyzed root tips of Vicia Faba 
Ussue, although it may live several weeks, develops no further and ultimately oS 
* Ueber Plasmavert 
pene ~ 3 © 
eee - Zellen. Jahrb. wiss. Bot. ; iu ' é 6 : 
