•604 



SCIENCE 



[N. S. Vol. XXX. No. 774 



•contains about eight volumes per cent, more 

 COj than the left heart. It seemed to us that 

 the electromotive force resulting from the dif- 

 ference in potential might exert an influence 

 •differing from the ordinary pharmacological 

 action of the carbonates and be, at least, a 

 factor in the maintenance of heart beat. 



The exact condition of the CO, in the blood 

 is not known. The fact that part is in solu- 

 tion and part is in combination renders a 

 mathematical presentation only approximate. 



Eight volumes per cent. CO, equals 80 vol- 

 umes per liter. Calculated from H as 0.0896 

 grams this would equal 1.9Y12 grams CO, 

 and equal 2.77Y7 grams of H^CO,, or approxi- 

 mately the equivalent of N /lO H^CO, be- 

 tween the left and the right sides of the 

 heart. Assuming this to be ionized we should 

 have an electromotive force represented by 

 the formula below. 



(Jones) T = .0002 "~^ T log ^ 



at 25° 0. or since the valence of the positive 

 negative ions may vary 



(Jones) 



— -0.00027' log -5^. 



To test the theory we perfused several 

 mammalian hearts (cats') with blood oxygen- 

 ated on one side and carbonated on the other. 

 The technical difficulties of keeping the two 

 separate were not completely overcome, but 

 sufficiently so to convince us that there was 

 no effect aside from the usual carbonate ac- 

 tion. 



Parts of the turtle ventricle or the whole 

 heart was split so that each end could be im- 

 mersed in a separate saline bath through 

 which COj and O could be forced. One end 

 was bathed in CO, and the other in O. The 

 whole was so arranged that a tracing could be 

 recorded. 



The results obtained were no different from 

 those with the mammalian heart. The ad- 

 dition of NaHCOj gave the same action irre- 

 spective of whether it was added to either or 

 both sides of the heart. Our results would 

 indicate that the difference in CO^ between 

 the left and right sides of the heart has no 



influence on the rate or strength of the beat 

 of the isolated organ. 



This does not preclude the probability that 

 CO, has an influence direct or indirect on the 

 heart beat of the intact animal. Its known 

 action on the dissociation of hemoglobin and 

 the probable similar action on other salts 

 renders the view highly probable that carbon 

 dioxide is a factor in the automatism of the 

 heart. Hugh McGuigan, 



E. H. NiOHOLL 



St. Louis, 



October 6, 1909 



THE INFLUENCE OF CHEMICALS IN STIMULATING 

 THE RIPENING OF FRUITS 



Various chemical and physical methods of 

 bringing on latent physiological processes in 

 plants have long been Itnown. Buds have 

 been brought into full blossom for commer- 

 cial purposes weeks before their natural time 

 by the application of anesthetics, and Molisch 

 has lately accomplished the same result by the 

 use of hot water. The Arabs have also ap- 

 plied cloths moistened with vinegar to 

 bunches of dates in order to " sweeten up " 

 retarded fruits. 



Following this lead, the writer has succeeded 

 in ripening the fruit of a seedling date into 

 a perfect commercial product in less than 

 three days. The flavor of the chemically 

 stimulated fruit is fully equal to that of the 

 best naturally ripened, and a much greater 

 evenness of ripening is obtained than when 

 left on the tree. The sprays of fruit are sub- 

 jected to the vapor of acetic acid for twelve 

 or fifteen hours. At the end of this time they 

 have become transparent nearly to the seed 

 and will then ripen naturally without further 

 treatment. The process can be accelerated by 

 exposing them to sunshine, or more rapidly 

 by heating for some hours to forty-five de- 

 grees centigrade. The process, it is antici- 

 pated, will permit the shipping of dates 

 green and ripening them at their destination 

 as bananas are now handled. 



The fresh ripe date is very soft and prone 

 to sour quickly, while the unripe fruit is very 

 firm and not easily bruised. Furthermore, the 



