Technique for the Observation of Protoplasmic Streaming in Sieve TubesAuthor(s): James SmallSource: New Phytologist, Vol. 38, No. 2 (Jul. 31, 1939), pp. 176-177Published by: Wiley on behalf of the New Phytologist TrustStable URL: http://www.jstor.org/stable/2428336 .

Accessed: 17/06/2014 09:43

Your use of the JSTOR archive indicates your acceptance of the Terms & Conditions of Use, available at .http://www.jstor.org/page/info/about/policies/terms.jsp

.JSTOR is a not-for-profit service that helps scholars, researchers, and students discover, use, and build upon a wide range ofcontent in a trusted digital archive. We use information technology and tools to increase productivity and facilitate new formsof scholarship. For more information about JSTOR, please contact support@jstor.org.

.

Wiley and New Phytologist Trust are collaborating with JSTOR to digitize, preserve and extend access to NewPhytologist.

http://www.jstor.org

This content downloaded from 185.44.78.76 on Tue, 17 Jun 2014 09:43:10 AMAll use subject to JSTOR Terms and Conditions

I76

TECHNIQUE FOR THE OBSERVATION OF PROTO- PLASMIC STREAMING IN SIEVE TUBES

BY JAMES SMALL Queen's University, Belfast

T X | HE explanation of the very high rate of translocation of carbohydrates is one of the outstanding problems of plant physiology.

In a successful endeavour to observe streaming of protoplasm, or at least movement of particles, in mature sieve tubes the writer has devised a delicate technique with which it may be possible to make extended observations. Meanwhile he is of the opinion that, with the publication of the technique, the field of experi- menters might be considerably widened.

The preparation of the tissue for observation is essentially a delicate operation. The elimination of the stoppage of streaming by shock, noted for other materials by Ewart (1903, pp. 72 sqq.), may require treatment as careful as that given to operations on the human eye. Acting upon this idea the writer had two ophthalmic lances, 2 mm. wide and 2 cm. long, specially made for these experirnents by Messrs Grieshaber of Schaffhausen, and also obtained from the stock of the same makers two other ophthalmic lances, 3 mm. wide and 3 cm. long.

Young plants of vegetable marrow were transplanted into large flower-pots, one to each pot, and tied up to canes as they increased in length. A plant in its pot was transferred from the garden to the laboratory bench. A straight internode about 5 in. long was selected in such a position on the stem that this internode could lie across the stage of a microscope without any strain. Two transverse cuts were made about half-way through the stem with a razor blade, and a single longitudinal cut was then made with the smaller Grieshaber knife. The exposed part of the stem tissue was then placed against the lower glass of a Watson's live-box. The whole stem on either side of the raised part of the live-box was then padded to fit, and bound with two rounds of tape to the brass base of the live-box. The part of the stern being operated upon was thus firmly fixed, with tap-water and saliva keeping the cut surface moist.

On the opposite side of the stem two further transverse cuts were made with the larger Grieshaber knife, rather closer than the first pair, and with the same knife a longitudinal cut was made which left a thin slice connecting the two parts of the stem. Finally, with the smaller ophthalmic lance, a single slicing cut was made, which left parts of the connecting tissue thin enough to be viewed through the microscope (about three or four cells thick). The cut surfaces were kept wet with tap water and a brush throughout these stages. Then the thin connecting strip was flooded with tap water and a cover-slip placed on top. All the longitudinal cutting

This content downloaded from 185.44.78.76 on Tue, 17 Jun 2014 09:43:10 AMAll use subject to JSTOR Terms and Conditions

Notes s77 had been done with the sharpest ophthalmic instruments known in Europe, on the principle that the sharper the cutting edge the smaller the shock during the operation.

Observations were made using a 6 in. objective. Small granules in the sieve tubes were seen to be in fairly rapid movement. The movements were mainly smooth, but sometimes a larger granule would cease movement temporarily and begin again. The smaller granules appeared to move faster than the larger granules.

Naturally with this successful first experiment the writer appealed to other observers. A laboratory assistant was able to check one set of movements, as to reality and apparent direction, and went on to observe other movements also. Prof. D. C. Harrison of the Department of Biochemistry, Queen's University of Belfast, also checked the reality of the movements, so that there can be no doubt that movements have been observed in the mature sieve tubes of Cucurbita Pepo var. vegetable marrow.

The movements occurred in quite a number of sieve tubes, and were observed in both directions, up and down the stem. The speed of movement of some of the larger granules was timed with a micrometer scale and a stop-clock. The speed varied from O I3 to perhaps i-o or more mm. per minute; o04 mm. per minute was the highest speed measured; more rapid movements were observed. The approxi- mate speed in mm. per minute for other materials are: Nitella 2-3, Vallisneria 0o7, Elodea o096 (Ewart, I903, p. 25). From the character of the movements it may be considered that the actual speed of the streaming may be higher than these first observations would imply, but this and other points, including the question of the observation of streaming in sieve tubes of other kinds of plants, involves careful development and extension of the technique which is here described.

REFERENCE

EWART, A. J. (I903). On the Physics and Physiology of Protoplasmic Streaming in Plants.

This content downloaded from 185.44.78.76 on Tue, 17 Jun 2014 09:43:10 AMAll use subject to JSTOR Terms and Conditions