1894. ] NEW YORK ACADEMY OF SCIENCES. 139 
and homogeneous mass, elongates, and a tail begins to form at 
the distal extremity of the cell—z. e., that which lies farthest 
from the center of the spermatosphere (figure 9). This elonga- 
tion of the nucleus continues until the spermatid becomes a 
long columnar cell with a filament growing out from one end, 
the other end remaining attached to the spermatosphere. The 
archoplasm mass now lies in a vesicle between the tail and the 
nucleus (figure 10). The further history is briefly as follows: 
The nucleus and tail elongate still more; the vesicle disappears 
by elongation of the archoplasm mass, and the spermatozoan 
finally assumes the shape of a long rod with a much longer fila- 
mentous tail (figure 11). This rod consists of middle piece and 
nucleus which can be differentiated only by careful staining. 
The history of the archoplasm mass has now been traced from 
its position in the spermatid to the mature spermatozoan, where 
it forms the middle piece. It has also been shown that the same 
substance (archoplasm mass) acts in a manner suggestive, at 
least, of an attraction center. This identity of archoplasm mass 
and middle piece of the spermatozoan furnishes a clue to the 
solution of the apparent contradiction between such cases as the 
echinoderms on the one hand and Aolofl on the other. I shall 
reserve for a future paper, however, the conclusions which may 
be drawn from the facts here recorded. 
STATED MEETING. 
February 19th, 1894. 
Professor A. H. CHESTER in the chair and thirty-seven per- 
sons present. 
SECTION OF GEOLOGY AND MINERALOGY. 
Professor Chester exhibited some fine crystals of Monticellite 
and Perofskite from Magnet Cove, Ark. 
Professor Kemp exhibited a nugget of native antimony 
from Kern Co., Cal. 
The following papers were read: 
“Preliminary Notice of Sodalite from three new Localities ” 
(Hastings, Ont., the Ural Mountains and the Congo Region), 
by L. Mel. Luquer. 
