From Professor A. B. Seymour, Harvard University

In his "Enumeration of the Peronosporeae of the United States," Professor Farlow says: "In this country the species of pythium have not been sufficiently studied, and no mention is made of them in this paper, although they possess a decided agricultural interest, since one species apparently causes what is known in some parts of the eastern states as the potting-bed fungus, which is very destructive to young house plants in the winter. Other species are known in decaying plants in damp ground." This is the extent of our knowledge of the subject in this country. In Europe there are several species of interest in this connection.*

In 1878 DeBary observed plants of Cleome violacea which turned brown near the surface of the ground and also in spots on the stem and leaves. The plants wilted and became foul or dried up. The next year they were worse and several additional species of flowering plants were attacked. All the discolored tissues were found to contain mycelium, sometimes of several kinds, but only one kind was present in every case and that was Phytoph-thora omnivora (or Pythium omnivora), a species closely allied to the potato rot fungus. Conidia-bearing branches of the mycelium (Fig. 1) grow out through the epidermis and the conidia germinate by forming zoospores (Fig. 2). The resting spores (Fig. 3) correspond to those of the grape mildew. I do not understand that this fungus lives in the soil.

Pythium is a fungus allied to phytophthora, but apparently lower in rank, Pythium vexans was found by DeBary growing on potato tubers which had already been partly rotted by the common potato rot fungus, Phytophthora infestans. He found that the pythium would not attack a healthy potato plant. It was also true that Phytophthora omnivora, though growing on a variety of plants, will not attack the potato. Fig. 4 shows part of the mycelium and two oospores of Pythium vexans, Fig. 5 is an oospore germinating by the formation of zoospores. Fig. 6 shows a similar spore germinating by forming a tube. Either process may occur.

•Bop. Gaz., 1883.

With regard to Pythium DeBaryanum, DeBary says:

"This pythium is, as Hesse has shown, a dangerous parasite. It is disseminated in garden soil to a remarkable degree. Therefore, one may be easily convinced that it almost always seizes upon plants subject to its attacks when they are sown in such earth and kept wet. One can be quite sure of obtaining the fungus by this means for examination at any time. The fungus may perhaps lie dormant in the earth in the form of mycelium, which it does at any rate in the form of resting conidia and oospores, which may retain their vitality through months of dryness. From the plant first attacked the mycelium spreads over the moist earth and then attacks the neighboring stock. The injury and death of seedling phaenogamous plants sown in wet places have in this, as Hesse has shown, almost always their immediate cause".

This species, then, is the one which will most likely prove to be the cause of damping-off in America. Fig. 7 contains an unripe oospore. Fig. 8 is one that has germinated.

Recent culture of the fungus which I have made confirms the supposition that damping-off is caused by fungi.

The figures are all from DeBary. Figures 1-3 represents various parts of Phytophthora or Pythium omnivora:

1, conidia (xgo); 2, germination of zoospores (X225); 3, a ripe oospore with remains of antheridium (X375). Figures 4-6 show Pythium vexans: 4, mycelium and oogonia (x6oo); 5, oospore germinating by formation of zoSspores (X300); 6, oospore germinating by formation of a tube (X300). Figures 7 and 8 are Pythium DeBary-anum: 7, oogonium containing unripe oospore, antheridium attached (X375); 8, germinating oospore (X250).

"A NEEDED EXPERIMENT".

After reading the article, "Some Literature," in the January number of The American Garden, in which the author presumes upon a wide acquaintance with experiment station literature, it is somewhat surprising to hear from the same source, under the heading "A Needed Experiment," in the February issue, that the question "how shall we cut our potatoes for seed," is "new and vital to the potato." True, it is vital to the potato grower, but it is very far from being "new" or a question that "has not already occupied the attention of scientists." There has been more than one man who, according to the writer of that article, is entitled to "be * * * * considered a benefactor of his race." Few subjects have received more attention from experimenters.

For at least one hundred years, investigators have been studying this question, and to-day the general testimony of experimental research is the same as when, in 1807, Mr. Dickson in his great work on agriculture, wrote: "It seems probable from the various experiments that have been made upon the subject, that the middle-sized whole potatoes, and the cuttings of large ones, are, in general, more productive than either the smaller sort of whole potatoes, small cuttings, or the eyes or shoots alone." In support of this statement Mr. Dickson gives tables showing the results of experiments carried on yearly from 1790 to 1795 (excepting 1793).

Long before experiment stations were established in this, or any other country, this subject had received attention, and we have only to examine the reports of the U. S. Department of Agriculture, beginning with the issue of 1847 from the Patent Office, to find that it has for many years been a live question among potato growers.

Referring simply to work on this subject at the experiment stations of this country, we can point to the records of more than thirty distinct trials, published in their reports and bulletins.

Many foreign publications, as well as the columns of our own agricultural papers, contain also the records of work in this line, performed by both public and private experiments.

It is now a well established fact, that, speaking in general terms, "the larger the amount of seed potato planted, the greater the corresponding crop." This does not mean that the crop is proportional to the seed planted, but simply that it increases to a certain extent as the amount of seed is made larger. When very large quantities of seed (forty to sixty bushels per acre) are planted, the increase is oftentimes not enough larger to pay for the increased cost of the seed. The most profitable amount of seed to plant is the medium ; that is a whole potato or a piece weighing three or four ounces and con-turning from two to four or five eyes. Experiments almost universally show that it is never safe to trust to a piece with only a single eye, per hill.

The above conclusions have been reached after care' ful study of all available records, and it will be seen that the principal one, regarding the proper amount of seed to plant, is not different from that recorded nearly a century ago. Several experiment stations are, at pre. sent, at work on the subject, and further data are continually being added to that already at hand.

Maryland Experiment Station. W. H. Bishop.

[We did not suppose it to be necessary to explain that R. T. Choke was writing in sarcastic vein ! - Ed. Am.G]