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the valves, and the subulate blank spaces so characteristic of A. Ralfsii are more or less apparent. Plate III, fig. 10.

I have been much puzzled where to put this diatom, which I have found only in this one filtering from Lake Erie water, it was associated with an abundance of Stephanodiscus Niagarae. At first sight it appears to be a Coscinodiscus, but as this genus is limited at present, it has many peculiarities that would prevent placing it here. Upon the whole, it seems to belong to Actinocyclus rather than to Coscinodiscus; in either case, its occurrence in fresh water is sufficiently remarkable, as all the members of these genera, hitherto known, are marine. As it has never been found in shore or inlet gatherings, and is very rare among the filterings, having never been found except in this one case, we might suppose, either that it came from an accidental disturbance of some ancient marine deposit in the Lake, or was living only at extreme depths, and passing into the ordinary water supply after some storm which had raised it nearer the surface. As it was living, and with the endochrome perfect, as in the Stephanodiscus, so that I was enabled to make careful drawings of it, we must dismiss the first supposition and conclude that it is one of those diatoms living at considerable depths, and which are only brought up by dredging, or storms. That diatoms flourish in immense abundance, notably the Coscinodisceœ, at great depths, is indicated by many of the "Tuscarora" soundings, some of these, from depths of over three miles, were almost wholly Coscinodiscus omphalanthus and its varieties, fully charged with endochrome; and belts of "diatom ooze" at considerable depths were also found by the Challenger" naturalists.

OBSERVATIONS ON SEVERAL FORMS OF
SAPROLEGNIEÆ.'

BY FRANK B. HINE, B. S.

(Received Sept. 28.)

THE following results of recent observations made upon this group are not claimed to be in all respects new to science. They are facts as I have found them, and are given not only on account of their peculiar and interesting character, but mainly because this family has received but

little notice in English publications, also to introduce the study of American forms, and treat of some that have not been described.

2

According to Lindstedt (4,39), the first mention of a form belonging to this group, is by Ledermüller, as early as 1760, who noted a form of Saprolegnia, probably S. ferax growОссаing upon a fly, and placed it among Confervaceæ. sional notices have since been made of them but the most extensive memoirs are by M. Cornu (2) in French, and H. Pringsheim in German (6), while among other writers Hildebrandt (3), De Bary, Reinke (9), Lindstedt (4), Thuret (8), have published various specific accounts.

The Saprolegnieæ are aquatic, parasitic, nearly colorless plants, appearing to the unaided eye merely as a light grayish, or white cushion-like mass of fine filaments.

I

They were placed by early investigators (3) (5) (8) among the Algæ, chiefly on account of the resemblance of their mode of reproduction to that in certain Algæ, and because they have also the same habitat. There is yet a diversity of opinion as to their true position; but later writers generally place them among the Fungi. made some experiments bearing on the determination of their position according to the distinctions of the two groups given by Rev. M. J. Berkeley (1), who says that "Fungi are distinguished from Algæ by deriving their nutriment from the substance on which they live, and not from the surrounding air or water-like Algæ; also by Julius Sachs (7) who states that "All Algæ contain chlorophyll, and have therefore the power of assimilation; all Fungi are destitute of chlorophyll, and are therefore parasites, or live on organized products of decomposition." Specimens of Menobranchus lanceolatus, kept in a tank at the University, became attacked by Saprolegna, which caused death; and while the animal was yet alive, by taking hold of the filaments of the plant, the skin, when infested, could be readily lifted, thus showing an inflamed portion beneath. Also, plants removed at different times from the matrix on which they grew showed

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1 The greater part of the material in this paper on the genera, Saprolegnia and Achlya is taken from my thesis for the degree B. S.

2A list of works referred to is given at the end of the paper. The first figure designates the number of the list. The last the page.

quite a plenteous mycelium. It is known that Achlya prolifera troubles the roe of fishes in some breeding-houses, causing much loss; also that forms of Saprolegna frequently attack fishes kept in aquaria, a good example of which is the following:

On August 31st, a number of fishes caught by means of a net, were placed in the University aquarium; on September 2d, some of the perch and sun-fish were attacked by this fungus, appearing at a little distance as if covered by a delicate veil, and the next morning died, when it was seen that the plant had formed a mat of mycelium over the whole animal. At another time some specimens with a small amount of the matrix were carefully removed and placed in distilled water, the result was growth equal to that which had taken place on those left in their normal condition; this can not be considered very satisfactory however, for the organic elements from the decomposing flesh would enter into the water, and thus tend to vitiate the experiment.

An experiment touching the point of assimilation was made as follows: a turtle which had died after being partly infested with Achlya racmosa, was placed in a dark closet for three days. The result was a very decided increase in growth, for, when

DESCRIPTION OF PLATE IV.

Fig. 1. Saprolegnia sp. natural size.

Fig. 2. Tip of growing filament.

Fig. 3. Tip of filament showing the aggregation of granules, and formation of the sporangium.

Fig. 4. Segmentation of the contents of the sporangium.

Fig. 5. Sporangium with zoospores formed.

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Figs. 12-18.

Figs. 19, 20.

Fig. 8. Another form of Saprolegnia showing zoospores held in old sacs.
Figs. 9-11. Zoospores at rest and germinated.

Showing rejuvinescence of zoospores.

Germination of same.

DESCRIPTION OF PLATE V.

Fig. 1.

Fig. 2.

Second sporangium formed on the same filament (350 diameters).
Terminal portion of a filament from a triton.

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Fig. 6.

A late sporangium of Saprolegnia sp. from a triton.

Fig. 7. Similar sporangia opening through longer tubes.

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