from its seat after the contact by the observer, the average person can surely make a contact as short as a thirtieth of a second, and some can always do better than this. Table II shows records of fair contacts obtained with a thimble and block. While the lengths of the shorter contacts of the average person seem to be rather less-when made in this manner than one two hundredth of a second, three of the persons (F, O, P) who made trial of the apparatus could surely make contacts the average lengths of which were only about one three hundredth of a second.

THE JEFFERSON LABORATORY,

CAMBRIDGE, MASS.

Proceedings of the American Academy of Arts and Sciences.

VOL. XLII. No. 5. — JUNE, 1906.

CONTRIBUTIONS FROM THE ZOÖLOGICAL LABORATORY OF THE MUSEUM OF COMPARATIVE ZOÖLOGY AT HARVARD COLLEGE. E. L. MARK, DIRECTOR.- No. 179.

SOME STAGES IN THE SPERMATOGENESIS OF THE HONEY BEE.

BY E. L. MARK AND MANTON COPELAND.

WITH A PLATE.

CONTRIBUTIONS FROM THE ZOÖLOGICAL LABORATORY OF THE MUSEUM OF COMPARATIVE ZOÖLOGY AT HARVARD COLLEGE. E. L. MARK, DIRECTOR. - No. 179.

SOME STAGES IN THE SPERMATOGENESIS OF THE HONEY BEE.

BY E. L. MARK AND MANTON COPELAND.

Presented May 9, 1906. Received May 1, 1906.

IN 1903 F. Meves published a short account of spermatogenesis in the honey bee in which it was held that the process was remarkably unlike that of other animals, and simulated in an interesting way the maturation of the female sexual products.

As is well known, an important parallelism between the formation of polar cells in the maturing egg and the last two cell divisions leading to the formation of spermatozoa was established for Ascaris by O. Hertwig, and has since been shown to be a general condition of maturation throughout the animal kingdom. But while in the sexual cells of the female maturation results in the formation of one functional and three (or two) non-functional elements, in the male the usual outcome. is four elements, the spermatozoa, all of which are functional.

In the honey bee Meves showed that the maturation divisions of the primary spermatocytes resulted, as in the case of the primary ovocyte generally, in the production of a single functional cell, inasmuch as there are produced from the primary spermatocyte in succession two "Richtungskörper." However, this fundamental difference was noted: whereas in the formation of polar cells during the maturation of the primary ovocyte there are produced two nucleated "Richtungskörper," in the spermatogenesis of the honey bee only the second of the corresponding bodies is nucleated, the first one being composed exclusively of cytoplasm.

At the time Meves published these observations we had already begun the study of the germinal cells in the male honey bee, and having now arrived at somewhat different conclusions from those set forth by him, will give here a preliminary account of our results thus far, the intention being to publish later a more detailed and comprehensive paper on the subject.

In the final generation of spermatogonia in the honey bee there is at the apex of each conical cell a spheroidal, nearly homogeneous body, which represents the remnants of the interzonal filaments of the preceding cell division. These bodies are stained black in iron haematoxylin, and on being washed out assume a characteristic yellowish gray color. Since they are admittedly the metamorphosed remnants of filamentous structures first named by Mark ('81, pp. 198, 539) interzonal filaments, we shall henceforth speak of them as the interzonal bodies. The interzonal body is identical with the "Zellkoppel " of Paulmier ('99, p. 228), to which Prowazek (:01, p. 201) has given the name Spindelrestkörper." It is to be noted that the term "Zellkoppel " was used by Zimmermann ('91, p. 189), who introduced the name into cytology, with a somewhat different meaning from that employed by Paulmier. This is in itself a reason for applying another name interzonal body to this structure.

At the end of the growth period, which follows the last spermatogonial division, the cells have increased greatly in size and have become in general spherical, a form which is more or less modified by the mutual pressure of the closely packed elements. At this stage (Figure 1) the interzonal body (a) is clearly visible, and is in contact with the cell membrane. Meves shows it in his Figure 1, but makes mention of it neither in his explanation of the figure nor in the accompanying text.

The first evidence of spermatocyte division is seen when the centrosome, which lies in contact with the cell membrane, divides and the two daughter centrosomes move apart along the periphery of the cell. The centrosomes during their migration appear to exert a marked influence on the form of the cell, which exhibits two more or less conspicuous elevations, the apex in each case being occupied by one of the centrosomes. Figure 2 represents a fairly early stage in the migration of the centrosomes and shows clearly the marked change in the form of the cell due to their presence. The distance between the two centrosomes increases until these ultimately arrive at opposite poles of the cell (Figure 3). Up to this time each centrosome seems to have exercised nearly the same amount of influence as the other in modifying the form of the cell; but from this time forward the influence of one is seen to predominate over that of the other, until at length (Figure 4) one end of the cell is drawn out into a long, slender, slightly tapering, finger-like process, at the tip of which is located the centrosome. This centrosome will be designated as the proximal one, the other as the distal centrosome.

The choice of these designations rests on a later condition in the