792 



SCIENCE 



[N. S. Vol. XL. No. 1039 



showed at that time areas of fully developed 

 sporangia which indicated that this organism 

 was a Myxomycete. A culture was submitted 

 to Dr. Thomas H. Macbride, who identified 

 the organism as Didymium xanthopus (Dit- 

 mar) Fr. 



Since the first appearance of this organism 

 cultures have been readily established by trans- 

 ferring small portions of the vegetative form 

 to fresh media, and also by sowing spores. At 

 the present time the third generation from 

 spores is growing luxuriantly and is furnish- 

 ing excellent material for further study of 

 this very interesting organism. It has been 

 possible to obtain practically all stages in the 

 formation of the sporangium by fixing mate- 

 rial taken every two hours during the process 

 of development. 



It can also be readily observed with the low 

 power microscope that the protoplasm exhibits 

 reversible streaming movements in somewhat 

 definite channels. This movement occupies 

 but a few seconds in each direction, first ac- 

 celerating and then retarding to a point of 

 rest before reversing. This feature will hare 

 some value to the teacher who wishes to demon- 

 strate protoplasmic streaming to students, for 

 it is superior to any other material observed 

 for this purpose. 



A more extensive report of morphological 

 and physiological studies of this organism 

 will be published at a later date. 



John P. Helyar 



EuTGEES College, 

 New Brunswick, N. J. 



THE EFFECT ON PLANT GROWTH OF SATURATING A 

 SOIL WITH CARBON DIO?:iDE 



The following note reports a greenhouse ex- 

 periment with corn and tomato plants where 

 the soil surrounding the roots was gradually 

 saturated with carbon dioxide, the aerial por- 

 tions of the plants being under normal condi- 

 tions throughout the experiment. The plants 

 were grown in six-inch earthenware pots in a 

 normal greenhouse soil. Both kinds of plants 

 grew uniformly and there was no choice be- 

 tween the individual corn or tomato plants 

 selected for the experiment. 



A bell-jar, about ten liters in capacity and 

 of the same shape as an ordinary aspirator 

 bottle, was placed over one of the tomato 

 plants. The earthenware pot containing the 

 plant was raised up so that as much as possible 

 of the plant was outside the jar. Absorbent 

 cotton was placed about the plant at the mouth 

 of the beU-jar. The bell- jar was put on a glass 

 plate smeared with vaseline. One of the corn 

 plants was treated in exactly the same way. 

 No carbon dioxide was added for a week and 

 the plants growing in the pots, enclosed by 

 the bell- jars, made as good growth as the check 

 plants. 



A steady stream of washed carbon dioxide, 

 of such speed that it gave two bubbles of gas 

 per second as it passed through the wash 

 bottle, was led into each of the bell-jars through 

 a side opening near the bottom of the jar. 

 This was continued for two weeks. 



The lower parts of the plants were affected 

 first and in a week the ill effects extended en- 

 tirely over the plants. The leaves drooped, 

 turned brownish, withered and curled up. The 

 veins of both treated plants darkened. The 

 plants were practically brown at the end of two 

 weeks' treatment, the tomato plant being more 

 physiologically ailected than the corn plant. 



After two weeks the side openings through 

 which the carbon dioxide had been introduced 

 were left open. The tomato plant soon damped 

 off at the mouth of the bell-jar, while the com 

 plant began to revive, sent out new growth and 

 at the end of a week was growing normally. 

 Two weeks after the treatment was discon- 

 tinued it had made ten inches of new growth. 



From the way the check plants grew, the 

 greenhouse temperature was satisfactory for 

 plant growth and the soil was a normal one. 

 The bell-jars did not produce the results, as 

 they did not inhibit growth before the carbon 

 dioxide was applied or after its application 

 was discontinued. A carbon dioxide saturated 

 soil upset the growth of these plants but did 

 not change the soil so that the plant could not 

 grow after its application was discontinued. 



H. A. Notes 

 Purdue Agricultukal Experiment Station, 

 Lafayette, Ind. 



