one direction this one appeared to be in a state of indecision. One end, which for convenience I shall call the anterior, was consistently trying to go in one direction. At the other end there was in progress an active formation of pseudopodia and an apparent endeavor to move in the opposite direction. The paren

chyma of the amoeba contained a rather larger amount of granular material than usual, and this was a little more abundant towards the posterior end.

The formation of pseudopodia at the posterior end was first in one direction (Fig. 1), and then in another (Fig. 1, a). This was accompanied by simultaneous formation of pseudopodia at the anterior end. The intracellular struggle which then ensued, during which the granular protoplasm flowed from the central region into both posterior and anterior pseudopodia, would continue for a few seconds, to be followed by the retraction of the pseudopodia and a few seconds of quiet. At last (Fig. 3), after two or three such trials, there appeared to ensue a determined struggle between the opposing ends of the animal. Soon the central portion became narrow and thread-like (Fig. 4). This connecting bond at last broke, and it was then seen that the animal had divided into two approximately equal parts. The part which had been the posterior region contained more than half of the coarse granules. The new individuals moved away from each other in opposite directions, each following the direction of its previous efforts. The one that had been the anterior end of the undivided animal not only contained fewer granules than the other, but it also had a larger proportion of clear protoplasm at its anterior end. It behaved normally and quickly moved out of the field. The other (Fig. 6), after moving in a normal manner for a few seconds, ceased to form pseudopodia, and assumed an irregularly spherical shape (Fig. 7).

Up to this point I supposed I had been witnessing an ordinary case of division. Then occurred what looked like the dissolution of this bit of supposedly immortal living substance. The ectosarc and protoplasm dis

Sketches of a dividing amœba made from memory a few minutes after the events which they illustrate had been observed. 1, la, pseudopodia at opposite ends of the animal with energetic flow of the endosarc in opposite directions; 2, cessation of struggle, movement in only one direction; 3, renewal of struggle with elongation of animal; 4, beginning of division; 5 and 6, division completed, 5 normal, 6 abnormal new amœba; 7, position assumed by 6 a few seconds later; 8, spontaneous disruption of 7. No nucleus was seen.

took place. The dense protoplasm increased in bulk rapidly until the ectosarc, no longer able to resist the pressure from within, gave way suddenly.

There was sufficient vegetable debris present to keep the specimen from being crushed by the cover-glass.

No signs of life could be seen in the disintegrated part. It was simply a cluster of granules with no coherence and no connecting material.

The length of the undivided animal was about 0.03 millimeter. Several other amabæ

of the same size and appearance were observed in the culture, but none were seen behaving in an abnormal way. As I did not realize that I had been witnessing anything unusual until the final catastrophe, the time occupied by the division and the subsequent events up to the disruption of the short-lived half was not noted. The whole operation lasted but a short time, probably little longer than one minute. EDWIN LINTON.

HOMING OF FISSURELLA AND SIPHONARIA.

The Patella is the only mollusc whose homing powers have been investigated. Fissurella, a rhipidoglossate prosobranch, and Siphonaria, which stands on the border line between the opisthobranchs and the pulmonates, while differing more or less widely from Patella in structure, closely resembles it in the form of the shell and in their littoral habits. It was, therefore, an interesting question whether they resemble it also in the possession of the homing power. A stay at the Bermuda biological station in the summer of 1903 gave an opportunity to answer this question, although a few days only being available for the investigation, it was by no means as complete as could be wished. Such as it is, however, I present it for the benefit of future students of the subject.

The specimens studied were Siphonaria alternata Say and Fissurella barbadensis Gmelin.' Both are abundant at Bermuda, where they live clinging to the exposed faces of the bare rocks between tide marks. Bare rocks, I say, for to a New England eye one of the most striking features of the Bermuda coast is the entire absence of the larger algæ, which upon our own rocky shores shelter so large and varied a fauna. The rocks are calcareous, soft and of irregular surface and the home of Siphonaria is recognizable by a greenish spot where the foot has rested. That of Fissurella, as my notes show, is also clearly marked, though I have carelessly omitted to note how it may be known. Both species, as will be seen from the following notes, exhibit undoubted though limited homing powers. 'These specimens were kindly identified for me by Mr. Charles W. Johnson of Boston.

In marking animals and scars Higgins's water-proof ink was used. White paint, which was used by Davis, was not accessible, but as the ink marks last about three days they are fairly satisfactory. Siphonaria, being comparatively small, was readily removed from its scar; Fissurella I was seldom able to detach uninjured, and, accordingly, my observations upon this species were limited almost entirely to watching its voluntary departures and returns. As might be anticipated, the animals, unlike Patella, remain motionless on their scars during low tide, moving, if at all, only when the incoming water has moistened and cooled their immediate surroundings.

One,

Siphonarias did not home when removed to a distance of more than six inches and were most likely to return when removed not more than two inches. A quiet and shallow tidepool furnished the most favorable conditions for their return. If the animal, on being transferred, was set down with its head away from the scar, it turned in the proper direction and, so far as I could judge, those headed away were quite as likely to get back as those headed toward the scars. In general, animals which lost their way seemed to crawl restlessly about for two or three days; each time one was visited it was found in a new place. however, settled down at once in a new home and at the end of the third day had made a discolored spot. On being transferred to his old home he apparently failed to recognize it and immediately crawled away. Usually the scar was recognized at once by a returning wanderer, and on reaching its edge he would turn about, if necessary, so that his shell might fit the scar, would slip on to it and settle down. Siphonaria alternata thus appears to have a sense of direction, the ability to recognize its own recently-left scar, and the power of homing when removed not more than six inches.

Experiments with Fissurella, as I have said, were usually unsuccessful. That these molluscs have the power of homing is seen, however, by watching them. As soon as the tide has so covered him that he is not exposed to the wash of the waves a Fissurella is very

Re

fitted with a black record silk ribbon. cently the Hammond Typewriter Company of New York has constructed, from the writer's specifications, a typewriter provided with a carbon ribbon and with ninety special characters designed for the preparation of line drawings to accompany geological and geographical papers. The same machine can be similarly used for statistical, engineering and other diagrams of a more or less mechanical and simple composition. Of course, this method should not wholly replace the use of the pen even, for example, in the differentiation of areas in a geological map or section. The ultra mechanical look of the typewritten legend can often be pleasingly relieved by the

The typewriter has its most general application in lettering, that most difficult element in line drawings. The particular machine made by the Hammond Company has the advantage of making it possible to employ a great range of type styles. Using the carbon ribbon, the writer has found that any one of the one hundred and twenty-five shuttles made for the machine (each shuttle bearing ninety characters and including the lettering for one of twenty-six different languages), will give an impression suitable for photographic reproduction. Each shuttle can be placed in the machine ready for work in a few seconds. The shuttles now on the market cost $2.50 each and any new character can be supplied

by the company at the cost of fifty cents. The ordinary Hammond machine furnished with a back-spacing key can be used for manuscript diagrams up to about eight inches in diameter, but the machine No. 6, fitted with a sixteen-inch roll, permits of the preparation of diagrams fourteen inches in diameter. The usual silk ribbon gives a 'woolly' line and is far less satisfactory than the carbon ribbon. A highly calendered and high grade linen paper of medium to heavy weight, or a thin Bristol board may be recommended. Often more than one impression of the key is necessary to obtain the required depth of tint for photography; such repeated impressions can be made at great speed by employing the back-spacing key. Care must be taken not to smudge the carbon of the completed printing.

The accompanying cuts serve to show something of the method as applied to geological diagrams. The diagram of alphabets and legends has been reduced to three fourths of its original diameters. The legends are intended to represent a few examples of those possible with the machine. They can be indefinitely increased in number and varied in design by the engraving of new characters on the shuttle and by using various permutations and combinations of the existing characters. The map is reduced to two thirds of its original diameters. It was copied from Harker's sketch map of the Carrock Fell District, published in the Quarterly Journal of the Geological Society of London, Vol. 51, 1895, Pl. IV. Here the geological formations could have been yet more clearly differentiated by cross-hatching with the ruling pen for one of them, but this particular drawing was made to illustrate the neatness and clearness of the machine-made production rather than to illustrate an ideal diagram. So far as the typewritten part of the drawings' is concerned, the use of the machine in preparing these illustrations represents a saving of from seventy-five to ninety per cent. of the time required by a draughtsman to duplicate the 'drawing.' R. A DALY. INTERNATIONAL BOUNDARY COMMISSION, OTTAWA, CAN.

MEETING OF THE BRITISH ASSOCIATION IN SOUTH AFRICA.

THE arrangements for the forthcoming meeting of the British Association in South Africa have now been completed, and Mr. Silva White, the assistant secretary of the association, sailed for Cape Town in the Walmer Castle, on Saturday last, July 1. The number of members who will proceed to South Africa to attend the meeting is 385, and of these no less than 276 members have intimated their intention to visit the Victoria Falls at the conclusion of the ordinary work of the association. The official party, consisting of leading representatives of science and guests of the association, with the general and sectional officers for this meeting and the president, numbers 140 in all, and will sail by the Saxon on July 29. Most of the other members will proceed to the meeting by the Durham Castle and the Kildonan Castle, both of which sail on July 22.

There will be receptions and social functions, excursions, etc., at Cape Town, Durham, Pietermaritzburg, Johannesburg, Kimberley and Bulawayo. The central organizing committee for South Africa (chairman, Sir David Gill, K.C.B., F.R.S., hon. secretary, Dr. Gilchrist) has carried out the coordinating work of the program. The lists of local committees and subcommittees contain nearly one thousand names, from which it may be concluded that much interest is taken in the meeting.

Lectures of a popular character will be delivered at the chief towns visited. These lectures have now been definitely arranged as follows:

Cape Town: 'W. J. Burchell's Discoveries in South Africa,' Professor Poulton; 'Some Surface Actions of Fluids,' Mr. C. V. Boys. Durban: Mountains: the Highest Himalaya,' Mr. D. Freshfield. Pietermaritzburg: 'Sleeping-sickness,' Colonel D. Bruce. Johannesburg: Distribution of Power,' Professor Ayrton; Steel as an Igneous Rock,' Professor Arnold. Pretoria: Fly-borne Diseases, Malaria, Sleeping-sickness, etc.,' Mr. A. E. Shipley. Bloemfontein: The Milky Way and the Clouds of Magellan,' Mr. A. R. Hinks. 1 From Nature.