BRIEFER ARTICLES 
THE OCCURRENCE AND RATE. OF PROTOPLASMIC 
STREAMING IN GREENHOUSE PLANTS 
In the Botanical Laboratory of Smith College, under the direction of 
Professor GANONG, various lines of investigation are in progress to determine 
which plants of those available during the school and college year are best 
adapted for educational work in each of the principal physiological 
processes. The results are appearing from time to time in the BOTANICAL 
AZETTE.! The object of the present inquiry is to discover which of such 
plants show protoplasmic movement, in which the streaming is most active, 
and at what temperatures. 
The development and sum of our knowledge of protoplasmic streaming — 
may be traced through Prerrer’s Plant physiology, which needs to be 
supplemented, however, by the references under ‘‘Protoplasmabewegung” 
in Just’s Jahresbericht, and by the admirable new work of Ewart, On 
the physics and physiology of protoplasmic streaming in plants (Oxford, 
Clarendon Press, 1903). Streaming has been found in a great number of 
plants of the most diverse groups, from fungi to phanerogams, and in the 
most different structures, including the exposed cells of algae (where it 
reaches its finest display), emergences and hairs on various organs (notably 
stamens), root hairs (where it has been found in at least sixty-five families), ; if 
plasmodia of myxomycetes, mycelia of molds, pollen tubes, the b' 
young wood, and medullary rays of various trees, stamens, petals, and 
other parts. The rate of the streaming has been measured by several 
observers in different plants, and ranges from zero up to an extreme of 
1om™™ per minute, but in each plant the rate is dependent-upon temperature 
and rises from a minimum of no movement up to an optimum of greatest 
movement, whence it sinks to a maximum of no movement, which cardinal — 
_ tory guesses range all the way from “pathological,” through ‘incidental, 
to “‘ecological,”’ the most reasonable of the latter (especially in view of its 
greater activity in large cells) being that it is a mechanical aid to diffusion. 
Protoplasmic streaming is a striking and perhaps a fundamentally — 
important phenomenon, well worth demonstration to elementary eet 
* 402302. 1905; 45:50. 1908; and 45:254. 1908. 
Botanical Gazette, vol. 46] 
