Year Book Volume 8 (Paperback)

This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1910 edition. Excerpt: ... in a physical way (as change in surface tension). Owing to the difficulty of obtaining and keeping ice at Tortugas, only a limited number of experiments could be performed. Temperatures of 24 to 34 were used in order to have the conditions as near normal as possible, and i m MgCl2 was tried first. At 34 the power of contraction and conduction was stopped about 2 to 2.5 times as soon as at 24. This indicates a combination of Mg with some muscle constituent, perhaps an Mg-proteid, and that the reaction velocity of this particular reaction has a temperature coefficient of about 2.5. The reverse experiment gave a very peculiar result. The strips of tissue were first placed in % m MgCl, at 29 for a certain time, then removed to sea-water at 24 and 34. The nerves always recovered instantly ( one-half minute), the muscles in times which indicate only a partial chemical temperature coefficient for one set of muscles. This can only be made clear by actual data which will be given in the complete paper. Here, then, is apparently a reversible process which proceeds in one direction with a chemical temperature coefficient, while in the reverse direction it is instantaneous (in the case of nerve-conduction), slow, but not following definitely a chemical temperature coefficient (in the case of muscle contraction). A few experiments, with 20 to 30 as the 10 interval, gave quite different results. Contraction was stopped at about the same time in the two solutions, in some cases sooner, at 20. Experiments in sea-water at 34 and 22 showed that contraction is not so vigorous as at 34, and I am inclined to believe that this might so lessen the time of activity in MgCl2 at 20 as to mask the chemical temperature coefficient. In other words, we are dealing with a...