I forbear at present to enter further into the particulars; nor have we had sufficient experience to speak decisively on the subject. I may, however, mention, that the idea of having recourse to this remedy in cholera, occurred to Dr. Latta, from being convinced, (which I am also,) that the evacuations upwards and downwards are in reality the serum of the blood; that it is the duty of the physician to replace it, as speedily as possible, by injecting a fluid, as similar to the serum as can be formed artificially, directly into the veins, which has been done here with wonderful, and, so far as we can yet judge, excellent effect. An immediate return of the pulse, an improvement in the respiration and in the voice, an evolution of heat, an improvement in the appearance of the patient, with a feeling of comfort, are the immediate effects. The quantity necessary to be injected will probably be found to depend upon the quantity of serum lost--the object of the practice being to place the patient in nearly his ordinary state, as to the quantity of blood circulating in the vessels.--I have, &c. (Signed) ROBERT LEWINS, M. D. TO W. MACLEAN, Esq. _Secretary to the Central Board of Health._ No. 2. SIR,--I did myself the honour to address a letter to you lately, on the effects of injecting a saline solution into the veins of a patient labouring under cholera. We have not frequent opportunities of trying this, which I denominate, admirable remedy, as the disease is decidedly less frequent here; but I have seen it employed in two other cases, in the course of the last two days, with the same excellent effect. Sixty ounces are generally thrown in at once, and repeated at the end of three or four hours. In a case to-day, where I saw fifty-eight ounces injected, (being the third time of performing the operation,) the patient’s pulse, at the commencement, was 180, very small, and very feeble. She was excessively restless, with a feeling of great weakness and tormenting thirst. Before twelve ounces were injected, the pulse began to improve; it became fuller and slower, and it continued to improve until, after 58 ounces had been injected, it was down to 110. Before I left the patient, (a woman,) her condition was altogether amazingly amended. There was a fine glow and a slight perspiration on her face; the veins on the back of her head were well filled; the restlessness was removed, the feeling of excessive weakness gone, and the thirst ceased. The pulse was under 100, free, full, and soft! Verily, sir, this is an astonishing method of medication, and I predict will lead to wonderful changes and improvements in the practice of medicine! I have addressed you upon the subject, as