Infusoria from the Moving Sands in the Neighborhood of San Francisco.
BY JAMES BLAKE, M.D., F.R.C.S.
The infusoria to which I would call the attention of the Society, were collected from the sands in the neighborhood of Point Lobos. These sands form a moving surface, which in dry weather is drifted by the prevailing winds from the shore of the ocean landwards, and are entirely devoid of any signs of vegetation for some distance from the shore. On walking over these sands when a strong north-west wind was blowing, a wind that does not bring up any fresh sand from the ocean beach at that part of the sand field, I noticed a number of small sized bodies projecting above the surface of the sand as it was being carried onwards by the wind. A closer examination showed that these bodies were formed of particles of sand, agglutinated together by some substance which rendered them almost black, and where dried possessing considerable tenacity. Some of these bodies projected as much as an inch and a half above the surface of the sand, with which however they all remained connected, forming generally small ridges. On examining a portion of this agglutinated sand under the microscope, the water with which I had moistened it was found to be full of infusoria, which commenced moving about as soon as the sand was moistened, although it had been quite dry for some days before being examined. These infusoria probably belong to the genus Monas, but they are so extremely minute that it was impossible to resolve them; they were, in fact, the smallest living infusoria I had ever examined. With a quarter-inch object glass of Powell and Lelands, they appeared as small globular moving bodies, although occasionally a movement would present one of them with apparently a narrow edge. Nothing much more definite could be made out with the microscope of my friend, Dr. Trask, when using an eighth object glass of Smith and Beck, as they could not be resolved into any form sufficiently definite to classify them. They appeared mostly as globular bodies moving about slowly, and presenting sometimes a longer axis, one end being larger than the other, and offering the appearance as if there was a semi-transparent mass attached to the larger end. The size was estimated at from a fifteenth to the twenty-thousandth of an inch. After a careful examination I was unable to detect any vegetable or organic nucleus which might have served as a nidus for these masses of infusoria. They would seem to become developed in the pure sand, or at least in the sand as it was blown up from the beach, after the salt had been washed out of it by the rain. [I would remark that it had been raining some days before I collected them.] Subsequent researches have shown that these infusoria are very generally diffused through the sands that form our drifting sand-hills around the city; and on examining some sand taken at a depth of fourteen feet from the surface, where the hills were being cut through, I found it full of well developed infusoria on placing it under the microscope a few minutes after it had been collected, so that there can be no doubt but that these infusoria were present in the sand at the time it was collected, where they had probably been in a torpid state for ages. It is possible that they might have been carried there by the infiltrating water during the rains; but I am inclined to think that they had been torpid there, as the circumstances in which they were placed were not favorable for propagation except by fission, a process that cannot be carried on indefinitely, even in these lower organisms. In fact, these infusoria, taken from the deep sands, copulated most extensively the moment they were placed in water. I am not aware that analogous observations have been made as to the office of these lower infusoria in fixing the moving sands, and thus initiating that series of changes by which they eventually become clothed with verdure; the first germs of organic life being generally supposed to be established by the lower vegetable organisms.
Dr. Kellogg presented the following paper: