sections of wood, and in our plate are represented by the largest openings. In some of the succulent plants, however, they are to be seen in a more striking manner. It is only necessary to tear a stalk of rhubarb or celery apart to find that fine fibres appear which are the last things to be ruptured ; these are the spiral ducts, and constitute the "stringiness" of old specimens of vegetables. In our wood shavings we also observe other points of interest, more especially if the sections be cut across the "grain" or direction of the main growth. First let us examine the upper of our figures (Pl. 10, fig. 1), which represents such a slice cut from a stick of oak. This has been taken from a common kind of wood and well representing the grand group of plants to which it belongs, that is to say the Exogens, or outside growers. Our lower figure, on the other hand, represents a section of a stem of sugar-cane, showing the mode of growth of an Endogen, or inside grower. And these two names at once designate the point upon which we wish to dwell; the mode of growth of woody stems as shown by means of the microscope. These figures have been carefully drawn from photographs taken for the purpose, and are, therefore correct representations of the objects. Looking now at our crossgrain shaving of oak, we notice first, scattered somewhat unevenly all over it, large openings, which are the spiral ducts; in some parts they appear to be more closely congregated together, forming, as it were, rows which are continuous after the manner of rings, increasing in dimensions from the centre of the stick towards the circumference. These show us how the wood grows. At first, when it is but a sapling, there is very little woody tissue present, as is evidenced from its fragility, and the moss of it is made up of simple cellular tissue. This constitutes the pith of the stem, and varies in dimensions in different plants; in the elder being very large, in the oak of small size. Through the large spiral ducts the sap freighted with matter for the building up of new tissues, is carried upwards to the leaves;

here it is brought in contact with the sunlight and air, and certain chemical changes take place in its composition. Downwards, through another set of ducts, it is carried just inside the bark, and here through its instrumentality, woody fibre is deposited, one fibre upon the other externally, and thus the twig grows by outside growth, becoming thicker and thicker each year. This addition of substance goes on during the spring and autumn months, the plant doing very much the same as human beings, that is to say, resting during the hot season. But when winter comes its growth is arrested entirely, and like the hibernating animals the tree sleeps. Now in animals the blood is carried by a set of vessels, known as arteries, to the lungs, where it comes in contact with the air inhaled, and has its composition so changed that it can build up new tissues. The same thing, essentially, we see, takes place in the tree, the leaves representing the lungs, or oxygenating organs. Now as the tree sleeps during the winter months here is an arrest of growth, and therefore when we examine such a cross-section of a piece of wood as we have given, we find a number-less or greater, according to the number of winters it has existedof these rings of arrested growth, and by counting them we can arrive at the age of such a stick of wood. So we see how the microscope assists in acquiring such a knowledge; and of course we shall find similar structure in all outside growers or Exogens. With inside growers the case is very different; for here the new matter is not deposited externally in regular rings; and, in fact we can, from a consideration of the facts we have related, readily understand why the Endogens are mostly confined to such portions of the globe where there are no cold months to arrest the growth. However, even in such climates, Exogens grow and rest also during a part of the year. We have given the two sections represented to show the very marked difference in these two modes of growth as illustrated by microscopic sections, and those who desire to verify our illustrations can readily do so

by cutting a slice of some green stem, when the sap is in the wood and it is therefore the more readily cut, and also taking a slice of some Endogen, the garden asparagus being an excellent plant for that purpose, and after placing them on a glass "slide" and moistening them with water, covering them with a piece of thin "covering glass," and then examining them with a microscope; even an ordinary pocket lens will often show these points of structure very well. Thus will the student of nature find instruction and amusement, knowledge and pastime, even in a shaving of wood cast off from a carpenter's jack-plane.

EXPLANATION OF PLATE 10.

Fig. 1. Section of oak wood cut transversely across the grain.
Fig. 2. Transverse section of sugar cane.

Both magnified 25 diameters.

NOTES ON SOME OF THE RARER BIRDS OF
MASSACHUSETTS.

BY J. A. ALLEN.

(Continued from page 519.)

GOLDEN EAGLE. Aquila chrysaetos Linn. (A. Canadensis auct.) A specimen was killed near Munson in November, 1864, and another near Deerfield, December 14th, 1865. The latter, a female, is said to have weighed thirteen and a half pounds, and to have measured seven feet and six inches in alar extent. It is now in the Springfield Museum of Natural History. Mr. J. G. Scott informs me that two specimens were captured near Westfield three years ago, one of which is in his cabinet.*

*In epist., Nov. 21, 1868.