With regard to general conditions such as the muscular and nervous irritability accompanying hysterical and neuraesthenic disturbances little can be said as to the possible value of calcium. Loeb drew attention to the possibilities of its being of use in these diseases, but there is not sufficient evidence to make any statement concerning it. The extreme irritability which is present in some types of insanity might also be tested in this respect.
Calcium might also be of benefit in asthma where the two distressing symptoms are spasmodic contractions of the bronchioles and a hypersecretion from the mucous membrane of the larger and smaller bronchi. Judging by analogy from the experiments described above, calcium should not only relieve the muscular contractions but also inhibit the secretion.
These suggestions are made simply in the hope of stimulating clinical research in this direction.
Wright has recently stated that calcium relieves urticaria, a circumstance which he refers to the influence of calcium on the coagulability of the blood, which he says is diminished in this condition. It seems more probable from the above experiments that the calcium inhibits the secretion or passage of fluid from the lymph vessels to form the vesicles.
CHAPTER XI.
The Action of Purgatives of Vegetable Origin.
This group of purgatives, as far as its general properties are concerned, is so well described in many text-books that it is unnecessary here to go into the details of their preparation and the commoner characteristics of each. Certain points which have come up in connection with my own experiments, however, may be briefly described here.
Cascara Sagrada is prepared in many ways, but the most favorable preparation for experiment is the dried extract. This is the dark yellow powder familiar in commerce. It is found that in shaking this powder in distilled water it is almost entirely insoluble. The result is a dirty yellow mixture, the filtrate from which gives an acid reaction. This suggested neutralizing the mixture or making it alkaline. A small amount of sodium bicarbonate was added, and the powder immediately went into solution, producing a clear dark brown fluid.[92] A similar result was obtained by adding sodium hydrate. It was found that ¹⁄₂ g. of the dried extract could be dissolved in 25 c.c. m/24 NaHCO3. This solution in NaHCO3, is practically neutral. If a few drops of dilute H2SO4 be added a yellow precipitate at once appears giving a mixture or suspension similar to that originally obtained by adding the powder to distilled water. The addition of NaHCO3 will again produce the characteristic dark brown solution. The extract is much more readily soluble in a stronger solution of NaHCO3.
The dried extract is thus soluble only in a neutral or alkaline fluid. It is insoluble in distilled water on account of the free acid which is present in the powder.
Cascara extract is readily soluble in the intestinal juice of a rabbit, a characteristic dark brown clear solution being obtained. On the other hand, it is insoluble in the gastric juice, and an alkaline solution added to the gastric juice is at once precipitated.
It was found that the intravenous injection of 1 c.c. of a 2% solution of cascara extract in m/25 NaHCO3 produces within a minute very strong peristaltic movements in the intestine. A similar injection of the same amount of m/25 NaHCO3 alone produces no such result, though stronger solutions of NaHCO3 cause a slight increase in intestinal movements. It is therefore the cascara in solution which produces these strong contractions.