doubt, having impressed something of its stature and form upon its seeds for resurrection of similar qualities in the following year. All this variation must have been the result of struggle for existence, for it is not conceivable that in less than two square feet of soil there could have been other conditions sufficiently diverse to have caused such marked unlikenesses; and I shall allow the plat to remain without defilement that I may observe the conflict in the years to come, and I shall also sow seeds from some of the unlike plants. From all these facts, I am bound to think that physical environment and struggle for life are both powerful causes of variation in plants which are born equal. Still, the reader may say, like Weismann, that these differences were potentially present in the germ, that there was an inherited tendency for the given red-root to grow three feet tall when 85 other plants were grown alongside of it in twenty inches square of soil. Then let us try plants which had no germ plasm, that is, cuttings from maiden wood. A lot of cuttings were taken from one petunia plant, and these cuttings were grown singly in pots in perfectly uniform prepared soil, the pots being completely glazed with shellac and the bottoms closed to prevent drainage. Then each pot was given a weighed amount of different chemical fertilizer and supplied with perfectly like weighed quantities of water. All weak or unhealthy plants were thrown out, and a most painstaking effort was made to select perfectly equal plants. But very soon they were unequal. Those fed liberally on potash were short, those given nitrogen were tall and lusty; and the variations in floriferousness and maturity were remarkable. data of maturity and productiveness were as follows: Phosphate of Sulphate of 18 blooms Phosphate of Check 67 days 27 blooms 26 blooms The Phosphate of Ammonia. 104 days 33 blooms Here then, is a variation of 39 days, or over a month in the time of first bloom, and of an average of 15 flowers per plant in asexual plants from the same stock, all of which started equal and which were grown in perfectly uniform conditions, save the one element of food. But these or similar variations in cuttings are the commonest experiences of gardeners. Whilst some philosophers are contending that all variation comes through sexual union, the gardener has proof day by day that it is not so. In fact, he does not stop to consider the difference between seedlings and sexless plants in his efforts to improve a type, for he knows by experience that he is able to modify his plants in an equal degree, whatever the origin of the plants may have been. Very many of our best domestic plants are selections from plants which are always grown from cuttings or other asexual parts. A fruitgrower asked me to inspect a new blackberry which he had raised. "What is its parentage?" I asked. "Simply a selection from an extra good plant of Snyder" he answered; that is, selection by means of suckers, not by seedlings. The variety was clearly distinct from Snyder, whereupon I named it for him. The Snyder plants were originally all equal, all divisions in fact, of one plant, but because of change of soil or some other condition, some of the plants. varied, and one of them, at least, is now the parent of a new variety. But even Mr. Weismann would agree to all this, only he would add that these variations are of no use to the next generation, because he assumes that they cannot be perpetuated. Now, there are several ways of looking at this Weismannian philosophy. In the first place, so far as plants are concerned in it, it is mere assumption, and, therefore, does not demand refutation. In the second place, there is abundant asexual variation in flowering plants, as we have seen; and most fungi, which have run into numberless forms, are sexless. In the third place, since all agree that plants are intimately adapted to the conditions in which they live, it is violence to suppose that the very adaptations which are directly produced by those conditions are without permanent effect. In the fourth place, we know as a matter of common knowledge and also of direct experiment, that acquired characters in plants often are perpetuated. I cannot hope to prove to the Weismannians that acquired characters may be hereditary, for their definition of an acquired character has a habit of retreating into the germ where neither they nor anyone else can find it. But this proposition is easy enough of proof, viz., plants which start to all appearances perfectly equal, may be greatly modified by the conditions in which they grow; the seedlings of these plants may show these new features in few or many generations. Most of the new varieties of garden plants, of which about a thousand are introduced in North America each year, come about in just this way. A simple experiment made in our greenhouses also shows the truth of my proposition. Peas were grown under known conditions from seeds in the same manner as the petunias were, which I have mentioned. The plants varied widely. Seeds of these plants were saved and all sown in one soil, and the characters, somewhat diminished, appeared in the offspring. Seeds were again taken, and in the third generation the acquired characters were still discernible. The full details of this and similar experiments are waiting for separate publication. The whole philosophy of "selecting the best" for seed, by means of which all domestic plants have been so greatly ameliorated, rests upon the hereditability of these characters which arise after birth; and if the gardener did not possess this power of causing like plants to vary and then of perpetuating more or less completely the characters which he secures, he would at once quit the business because there would no longer be any reward for his efforts. Of course, the Neo Darwinians can say, upon the one hand, that all the variations which the gardener secures and keeps were potentially present in the germ, but they cannot prove it, neither can they make any gardener believe it; or, on the other hand, they can say that the new characters have somehow impressed themselves upon the germ, a proposition to which the gardener will not object because he does not care about the form of words so long as he is not disputed in the facts. Weismann admits that "climatic and other external influences" are capable of affecting the germ, or of producing "permanent variations," after they have operated "uniformly for a long period," or for more than one generation. Every annual plant dies at the end of the season, therefore whatever effect the environment may have had upon it is lost, unless the effect is preserved in the seed; and it does not matter how many generations have lived under the given uniform environment, for the plant starts all over again, de novo, each year. Therefore, the environment. must affect the annual plant in some one generation or not at all. It seems to me to be mere sophistry to say that in plants which start anew from seeds each year, the effect of environment is not felt until after a lapse of several generations, for if that were so the plant would simply take up life at the same place every year. This philosophy is equivalent to saying that characters which are acquired in any one generation are not hereditary until they have been transmitted at least once! My contention then, is this: plants may start equal, either from seeds or asexual parts, but may end unequal; these inequalities or unlikenesses are largely the direct result of the conditions in which the plants grow; these unlikenesses may be transmitted either by seeds or buds. Or, to take a shorter phrase, congenital variations in plants may have received their initial impulse either in the preceding generation or in the sexual compact from which the plants sprung. Cornell University, Ithaca, N. Y. A COMPARATIVE STUDY OF THE POINT OF ACUTE VISION IN THE VERTEBRATES.1 BY J. R. SLONAKER, Fellow in Biology, Clark University. In this preliminary sketch of a comparative study of the eyes of vertebrates, with special reference to the fovea centralis or point of acute vision, I shall first give the processes and methods of preparation which I have used and results obtained, and, second, the position of the area centralis as indicated by the retinal arteries. The microscopic descriptions and the relation of the position and shape of the eye and arrangement of the retinal elements to the habits of the animal will follow in a later paper. 'I wish to thank Dr. C. F. Hodge for valuable assistance and for his method of injecting the eye-ball, thus preserving it for complete sections. I am also very much indebted to Clark University for valuable aid and for apparatus and materials to further this study. For microscopical purposes and best results it is necessary to obtain the eye fresh, at least not later than an hour after death, and subject it to the action of certain hardening liquids which will permeate and preserve without causing the retina to swell and become wrinkled. With some animals it is quite easy to preserve the retina without its becoming wrinkled or floated off (fishes, amphibians, reptiles, and some mammals), while with others (most mammals and birds) it is a more difficult task. In order to prevent this folding and floating off of the retina, the eye is injected under pressure and immersed at the same time in a bath of hardening fluid. It is carried thus on up through the different percentages of alcohol and imbedded in celloidin. A more minute description of the method is as follows: Fig. 1 represents a rack with movable shelves, on which are placed bottles A and A', containing the same fluid as bottles B and B', and provided with siphons to connect with glass cannulas. In order to insert the cannula, a hole is carefully drilled about the equator and on a meridian perpendicular to the plane in which it is desirable to obtain sections. The perforation is stretched open, rather than cut, so the sclerotic will clasp the neck of the cannula tightly. A convenient instrument for this operation. is a spear-pointed dissecting needle, and not |