NORTH AMERICAN ANTHURUS. 493 



(Figs. 16 and 17). In some places these folds have their surface thrown into a 

 secondary series. Here the small depressions of these folds extend into the primary 

 fold in the direction that the hyphal branches must have originally taken in passing 

 toward the surface of the cavity from the deeper tramal tissue of that primary fold. 

 The impression gained from the branched structure of the chambers is that originally 

 simple chambers have had branches form in the tissue of the gleba through the gradual 

 spreading apart of the masses of hyphae which reached to the surface of the first 

 chambers, and that this spreading apart followed from the need of a greater surface 

 consequent upon the abundant production of basidia in the region of the existing 

 chambers. That the formation of the basidia causes the formation of branches of the 

 chambers, seems to be shown by the fact that the most remote portions of the branch- 

 chambers are constantly lined with the basidia. That the basidia form only in the region 

 of already existing chambers seems to be shown by the fact, that upon running through 

 the series of cross sections, small chambers are not found absolutely isolated from the 

 large chambers. They may seem so isolated in some sections, but others show the 

 connection. 



How has there arisen from the simple conditions of the cortical and medullary 

 tissues in the mycelial strand the more complicated and yet symmetrical disposition of 

 these tissues in the egg just described ? How have the six masses of the gelatinous 

 layer of the peridium come to be separated from each other by plates of cortical 

 tissue ? How happens it that these masses of gelatinous tissue are connected with 

 the medullary tissue from which they originate, only in the upper part of the egg ? 

 Was there a connection down to the base in a younger stage ? 



Determination of Earlier Development by Reference to Clathrus. 



No younger egg of Anthurus is available for a direct answer to these questions, yet 

 the stage of development just described bears in certain features so much in common 

 with the better known genus Clathrus that approximately correct answers may 

 nevertheless be had. 



The earlier conditions of Clathrus cancellatus have been examined and illustrated by 

 Fischer. 1 His earliest stage (Taf. 1, fig. 1) shows the medullary tissue of the mycelial 

 strand spreading out in the pyriform egg and sending several radiating branch-like 

 masses into the cortical region. Broad masses of cortical tissue occupy the spaces 

 between these branches. In a slightly older stage the medullary branches have by 

 growth become much broader in their peripheral portion and have crowded the separating 



1 Ed. Fischer: Untersuch. z. entwick. tier phalloideen, p. 3, taf. 1 unci 2, fiij. 1-7. 



