Your very kind letters of May 22d and 23d have both been received. Please say to Dr. Finlay that I will send a copy of our last paper just as soon as we can get it from “American Medicine.” It hasn’t been published yet. I hope to have it soon. You shall certainly have a Reprint. What you tell me about the y.-f. situation is certainly very encouraging, _but_ were not the _results_ just as encouraging in _1899_, at the same season? I will admit that you must have more non-immunes in Havana now than in 1899. Of course, you understand, my dear Doctor, that the control of yellow fever during this epidemic season, is to me the all-absorbing and important question, and it is on this very account that I am afraid that you and I might be led, in our enthusiasm, to think that more should be attributed to the sanitary measures now being carried out, than to the season, or some other conditions of which we might be ignorant. It is simply a delight to read that you are “in high fettle,” and I consider the city fortunate in having a Health Officer who believes that he can master the problem. I am astonished at the strength of your mosquito-destroying sanitary squad. What you say about the cesspools as breeding-places is intensely interesting. We got our first good supply of larvæ from an old can containing some feces at Columbia Barracks, and since then we have added a little fecal material to our breeding jars and have found that larvæ thus fed grew much more vigorously than those in ordinary water. Your experiments agree fully with ours. You are certainly doing effective work toward their destruction. I was astonished at the amount of pyrethrum that you are burning to the 1,000 cubic feet. Is such a large amount necessary, do you think? Won’t you soon exhaust the supply? At Mount Vernon B’ks, where culex was very abundant, I used to find that about 2 or 3 ounces would intoxicate every mosquito in a room of some 3,500 cubic feet, so that I could sweep them up and burn them before they “sobered up.” Certainly your plan of destroying insects in the surrounding houses is worthy of all commendation. However, be sure that your sanitary measures do not prove obnoxious to the Cuban doctors and laymen, or otherwise they will certainly conceal their milder cases. While the destruction of the mosquitoes is very desirable, I consider the thorough protection of the patient against their bites as of even greater importance. I cannot believe that in so largo a city ... that you can possibly accomplish this. The undertaking, to me, seems well-nigh impossible. They _will_ conceal their cases, _do what you may_; and these cases will be the foci for other cases. I can see no other alternative for this summer, at least. Still, you will undoubtedly be able to control the spread of the disease better than ever.... Pardon this long letter. Good luck attend your well-conceived regulations. Health and happiness attend you and yours. Sincerely, your friend, REED.