Observations in Washington, D. C., September 5, 1879, 8:35 A.M., Boston time, near Congressional Cemetery.

1. Seized with sneezing on my way to cemetery. Examined nasal excretions and found no Palmellae.

2. Pool near cemetery. Examined a spot one inch in diameter, raised in center, green, found Oedegonium abundant. Some desmids, Cosmarium binoculatum plenty. One or two red Gemiasmas, starch, Protuberans lamella, Pollen.

3. Specimen soft magma of the pool margin. Oedogonium abundant, spores, yeast plants, dirt.

4. Sand scraped. No organized forms but pollen, and mobile spores of some cryptogams.

5. Dew on grass. One stellate compound plant hair, one Gemiasma verdans, two pollen.

6. Grass flower dew. Some large white sporangia filled with spores.

7. Grass blade dew, not anything of account. One pale Gemiasma, three blue Gemiasmas, Cosmarium, Closterium. Diatoms, pollen, found in greenish earth and wet with the dew. Remarks: Observations made at the pool with clinical microscope, one-quarter inch objective. Day cloudy, foggy, hot.

8. Green earth in water way from pump near cemetery. Anabaina plentiful. Diatoms, Oscillatoriaceae. Polycoccus species. Pollen, Cosmarium, Leptothrix, Gemiasma, old sporangia, spores many. Fungi belonging to fruit. Puccinia. Anguillula fluviatilis.

9. Mr. Smith's blood. Spores, enlarged white corpuscles. Two sporangia? Gemiasma dark brown, black. Mr. Smith is superintendent Congressional Cemetery. Lived here for seven years. Been a great sufferer with ague. Says the doctors told him that they could do no more for him than he could for himself. So he used Ayer's ague cure with good effect for six months. Then he found the best effect from the use of the Holman liver ague pad in his own case and that of his children. From his account one would infer that, notwithstanding the excellence of the ague pad, when he is attacked, he uses blue mass, followed with purgatives, then 20 grains of quinine. Also has used arsenic, but it did not agree with him. Also used Capsicum with good results. Had enlarged spleen; not so now.

2d specimen of Mr. Smith's blood. Stelline, no Gemiasma. 3d specimen, do. One Gemiasma. 4th specimen. None. 5th specimen. Skin scraped showed no plants. 6th specimen. Urine; amyloid bodies; spores; no sporangia.

United States Magazine store grounds. Observation 1. Margin of Eastern Branch River. Substance from decaying part of a water plant. Oscillatoriaceae. Diatoms. Anguillula. Chytridium. Dirt. No Gemiasma.

Observation 2. Moist soil. Near by, amid much rubbish, one or two so-called Gemiasmas; white, clear, peripheral margin.

Observation 3. Green deposit on decaying wood. Oscillatoriaceae. Protuberans lamella, Gemiasma alba. Much foreign matter.

Mr. Russell, Mrs. R., Miss R., residents of Magazine Grounds presented no ague plants in their blood. Sergeant McGrath, Mrs. M., Miss M., presented three or four sporangias in their blood. Dr. Hodgkins, some in urine. Dr. H.'s friend with chills, not positive as to ague. No plants found.

Observations in East Greenwich, R.I., Aug. 16, 1877.

1. At early morn I examined greenish earth, northwest of the town along the margin of a beautiful brook. Found the Protuberans lamella, the Gemiasma alba and rubra. Observation 2. Found the same. Observation 3. Found the same.

Observation 4. Salt marsh below the railroad bridge over the river.

The scrapings of the soil showed beautiful yellow and transparent Protuberans, beautiful green sporangias of the Gemiasma verdans.

Observation 5. Near the brook named was a good specimen of the Gemiasma plumba. While I could not find out from the lay people I asked that any ague was there, I now understand it is all through that locality.

Observation at Wellesley, Mass., Aug. 20, 1877.

No incrustation found. Examined the vegetation found on the margin of the Ridge Hills Farm pond. Among other things I found an Anguillula fluviatilis. Abundance of microspores, bacteria. Some of the Protococci. Gelatinous masses, allied to the protuberans, of a light yellow color scattered all over with well developed spores, larger than those found in the Protuberans. One or two oval sporanges with double outlines. This observation was repeated, but the specimens were not so rich. Another specimen from the same locality was shown to be made up of mosses by the venation of leaves.

Mine host with whom I lodged had a microscopical mount of the Protococcus nivalis in excellent state of preservation. The sporangia were very red and beautiful, but they showed no double cell wall.

In this locality ague is unknown; indeed, the place is one of unusual salubrity. It is interesting to note here to show how some of the algae are diffused. I found here an artificial pond fed by a spring, and subject to overflow from another pond in spring and winter. A stream of living water as large as one's arm (adult) feeds this artificial pond, still it was crowded with the Clathrocyotis aeruginosa of some writers and the Polycoccus of Reinsch. How it got there has not yet been explained.

The migration of the ague eastward is a matter of great interest; it is to be hoped that the localities may be searched carefully for your plants, as I did in New Haven.

In this connection I desire to say something about the presence of the Gemiasmas in the Croton water. The record I have given of finding the Gemiasma verdans is not a solitary instance. I did not find the gemiasmas in the Cochituate, nor generally in the drinking waters of over thirty different municipalities or towns I have examined during several years past. I have no difficulty in accounting for the presence of the Gemiasmas in the Croton, as during the last summer I made studies of the Gemiasma at Washington Heights, near 165th St. and 10th Ave., N.Y.

Plate VIII. is a photograph of a drawing of some of the Gemiasmas projected by the sun on the wall and sketched by the artist on the wall, putting the details in from microscopical specimens, viewed in the ordinary way. This should make the subject of another observation.

I visited this locality several times during August and October, 1881. I found an abundance of the saline incrustation of which you have spoken, and at the time of my first visit there was a little pond hole just east of the point named that was in the act of drying up. Finally it dried completely up, and then the saline and green incrustations both were abundant enough. The only species, however, I found of the ague plants was the Gemiasma verdans. On two occasions of a visit with my pupils I demonstrated the presence of the plants in the nasal excretions from my nostrils. I had been sneezing somewhat.

There is one circumstance I would like to mention here: that was, that when, for convenience' sake, my visits were made late in the day, I did not find the plants abundant, still could always get enough to demonstrate their presence; but when my visits were timed so as to come in the early morning, when the dew was on, there was no difficulty whatever in finding multitudes of beautiful and well developed plants.

To my mind this is a conclusive corroboration of your own statements in which you speak of the plants bursting, and being dissipated by the heat of the summer sun, and the disseminated spores accumulating in aggregations so as to form the white incrustation in connection with saline bodies which you have so often pointed out.

I also have repeated your experiments in relation to the collection of the mud, turf, sods, etc., and have known them to be carried many hundred miles off and identified. I have also found the little depressions caused by the tread of cattle affording a fine nidus for the plants. You have only to scrape the minutest point off with a needle or tooth pick to find an abundance by examination. I have not been able to explore many other sites, nor do I care, as I found all the materials I sought in the vicinity of New York.

To this I must make one exception; I visited the Palisades last summer and examined the localities about Tarrytown. This is an elevated location, but I found no Gemiasmas. This is not equivalent to saying there were none there. Indeed, I have only given you a mere outline of my work in this direction, as I have made it a practice to examine the soil wherever I went, but as most of my observations have been conducted on non-malarious soils, and I did not find the plants, I have not thought it worth while to record all my observations of a negative character.

I now come to an important part of the corroborative observations, to wit, the blood.

I have found it as you predicted a matter of considerable difficulty to find the mature forms of the Gemiasmas in the blood, but the spore forms of the vegetation I have no difficulty in finding. The spores have appeared to me to be larger than the spores of other vegetations that grow in the blood. They are not capable of complete identification unless they are cultivated to the full form. They are the so-called bacteria of the writers of the day. They can be compared with the spores of the vegetation found outside of the body in the swamps and bogs.

You said that the plants are only found as a general rule in the blood of old cases, or in the acute, well marked cases. The plants are so few, you said, that it was difficult to encounter them sometimes. So also of those who have had the ague badly and got well.

Observation at Naval Hospital, N.Y., Aug., 1877. Examined with great care the blood of Donovan, who had had intermittent fever badly. Negative result.

The same was the result of examining another case of typho-malarial (convalescent); though in this man's blood there were found some oval and sometimes round bodies like empty Gemiasmas, 1/1000 inch in diameter. But they had no well marked double outline. There were no forms found in the urine of this patient. In another case (Donovan,) who six months previous had had Panama fever, and had well nigh recovered, I found no spores or sporangia.

Observations made at Washington, D.C., Sept., 1879. At this time I examined with clinical microscope the blood of eight to ten persons living near the Congressional Cemetery and in the Arsenal grounds. I was successful in finding the plants in the blood of five or more persons who were or had been suffering from the intermittent fever.

In 1877, at the Naval Hospital, Chelsea, I accidentally came across three well marked and well defined Gemiasmas in the blood of a marine whom I was studying for another disease. I learned that he had had intermittent fever not long before.

Another positive case came to my notice in connection with micrographic work the past summer. The artist was a physician residing in one of the suburban cities of New York. I had demonstrated to him Gemiasma verdans, showed how to collect them from the soil in my boxes. And he had made outline drawings also, for the purposes of more perfectly completing his drawings. I gave him some of the Gemiasmas between a slide and cover, and also some of the earth containing the soil. He carried them home. It so happened that a brother physician came to his house while he was at work upon the drawings. My artist showed his friend the plants I had collected, then the plants he collected himself from the earth, and then he called his daughter, a young lady, and took a drop of blood from her finger. The first specimen contained several of the Gemiasmas. The demonstration, coming after the previous demonstrations, carried a conviction that it otherwise would not have had.