Biological Papers. 133 



The recently discovered species, Diocn purpusii, is found near 

 Tomellin, 300 miles south of the city of Puebla. 



Dioon is dioecious, each individual bearing a single cone at the 

 apex of the stem. The ovulate cone is much larger than the stam- 

 inate, and constitutes one of the most interesting features of this 

 interesting tree. The average cone is about nine inches in length, 

 six inches in diameter, and weighs about ten pounds. The mega- 

 sporophylls are large and relatively long and are covered with 

 rementum, a coarse, hairy growth which serves as a splendid pro- 

 tective coat. The cone is somewhat looser in make-up than the 

 ovulate cone of the pine. Two megaspores are borne at the base 

 of each sporophyll, thus giving to the tree the name Dioon, which 

 means two eggs. The cone displayed herewith is smaller than the 

 average, being somewhat dwarfed in the upper sporophylls. It was 

 picked in July, near Chavarrillo, sent by parcels post to Chicago, 

 and carried in a grip to Ottawa in August. Since tliat time it has 

 been kept by the writer in the cellar. It shows no sign of mold or 

 decay. In fact, it is green ; so it is safe to say that the gameto- 

 phytes are still alive and would make interesting histological 

 material. 



The staminate cones are much smaller, as has been indicated, 

 and are less conical in shape than the ovulate ones. The collector 

 would scarcely notice them among the leaves in their natural posi- 

 tion, as they have very short bases, which do not elevate them above 

 the leaves enough to be seen well from the ground. In July they 

 appear full grown and present a very solid, definite form, with sporo- 

 phylls regularly arranged in spirals. In the accompanying photo- 

 graph a few of the topmost leaves have been cut away in order to 

 display the cone. Later the cone lengthens and falls over to one 

 side, while the pollen is shed abundantly. The pollen is produced 

 in microsporangia situated on the upper side of the sporophylls. 

 Several hundreds of these microsporangia are borne on a single 

 microsporophyll, so that the pollen grains are produced in great 

 profusion. 



We are indebted to Doctor Chamberlain, of the Hull Botanical 

 Laboratory, Chicago, for definite knowledge of the morphology of 

 Dioon edule. With the aid of a grant from the Botanical Society 

 of America he visited Mexico several times to collect material for 

 research. Governor Theodore A. Dehesa, of Vera Cruz, and Alex- 

 ander M. Gaw, of the State Bureau of Information, at Jalapa, have 

 cooperated heartily in the work of securing suitable specimens for 



