142 r REPORT—1858. 
of cells; on the inner surface the choroid, of true hexagonal cells; and in the tissue, 
and on the posterior surface, of stellate cells. The use of these cells was to destroy 
the light as soon as it had acted on the retina; and they were the most perfect 
absorbers of light of any substance in Nature that he knew of. From the account 
he gave of the arrangement of the pigment, it afforded what he considered a satis- 
factory anatomical explanation of an abnormal condition of the eye which had 
hitherto not been understood, viz. AZusce volitantes. The figures of those motes he 
believed to resemble exactly portions of the choroid coat when teazed out; and they 
might be expected to appear and disappear with the varying condition of the vessels 
arising from disordered stomach or the cerebral circulation, and be cured by what- 
ever corrects those conditions; or the muscz might result from different organic 
changes in the choroid coat, which are incapable of being removed. 
On the Results obtained from an Extended Inquiry into the Quantity of 
Carbonic Acid evolved from the Lungs under the Influence of various 
Agents, By Dr. E. Smiru. 
The author gave a general account of a large series of experiments in which he had 
sought to determine the true amount of carbonic acid expired and of air inspired, with 
the rate of pulsation and respiration under numerous conditions, as, for example, in 
the twenty-four hours with the ordinary meals, during sleep, with different and de- 
finite kinds of exertion, during a prolonged fast, at various periods of the year, and 
under the influence of all ordinary kinds of food when taken separately and alone, 
He had collected all the carbonic acid expired during eighteen consecutive hours, 
with short intervals for meals, and had determined the amount expired in profound 
sleep in the night, viz. one-half of the average quantity of the day, There was a 
very slight and gradual increase after 3 a.m. until the hour of breakfast, and during 
the day there was always a rapid increase after each meal, and particularly after 
breakfast and tea, followed by a subsidence to the original amount before the next 
meal, if the meals were not too frequent. Whilst fasting (twenty-seven hours), 
the quantity was uniform throughout the whole period. 
He found that the quantity of carbonic acid expired varied most materially under 
the influence of different kinds of food, states of the atmosphere, season, &c. During 
the summer the respiration is }th less than during the colder months of the year; 
and although the skin exercised most important functions, he found that it was not 
vicarious of the action of the lungs in the expiration of carbonic acid; for while 
the lungs expired 600 grains, the skin threw off only 6 grains. The increase in the 
quantity of carbonic acid after partaking of arrow-root was yery small, but it was 
much greater after eating oatmeal and rice; whilst wheat flour produced the greatest 
quantity, though the increase was less enduring than with oatmeal and rice. Tea, 
coffee, cocoa, and chickory were found to be respiratory exciters, and consequently 
increased the waste of the system, and could not be classed as food. As tea also’ 
induced perspiration, it was most valuable as a remedy against the action of heat, 
and would also be useful in cases of drowning and interrupted respiration. Tea 
caused the evolution of much more carbon than it supplied. Brandy, sometimes ad- 
ministered in cases of drowning, had the very opposite effect to that desired, since 
it lessened respiration; whereas tea increased the action both of the lungs and skin, 
If the object were to prevent the waste of the system, then alcohol might be useful, 
and tea would be improper. Both sugar and milk greatly increased the respiratory 
functions. The experiments made showed that those who were more susceptible of 
the influence of heat, were the least able to bear change to hot climates; and if this 
were borne in mind, it would be found of service to those who might contemplate 
going abroad. 
On the Methods hitherto adopted for the Determination of the Carbonic Acid 
contained in the Expired Air, with the Description of a new Method. By 
Dr, E. Smiru. 
The author gave a brief account of the various methods which have been employed 
since the time of Lavoisier, and particularly those of Prout, Vierordt and Bocker ; 
