494 EDWARD A. BURT ON A 



cortical portions into narrow plates. These stages bring the development up to the 

 conditions shown in Fischer's Figs. 3 and 4, which are quite similar to my Fig. 16 except 

 perhaps in the case of the fundament of the arm. 



These early stages of C. cancellatus rather indicate that the arrangement in the 

 peridium of masses of gelatinous tissue separated from each other by plates of cortical 

 tissue has resulted from the extrusion into the early cortical layer of masses of more 

 vigorously growing medullary tissue; still such stages do not forbid the interpretation 

 that the cortical tissue has taken the initiative and has intruded into the medullary 

 i-egion forming the plates. 



The supply of Clathrus columnatus Bosc, to which reference has been made on a 

 preceding page, contained one egg in an earlier stage than those of C. cancellatus described 

 by Fischer. CfatJirus columnatus in its mature form is characterized by a receptaculum 

 having usually four meridionally ascending arms which are joined together into two 

 opposite pairs above, and then these pairs are joined together by a single connecting 

 portion. The youngest egg of this species, as taken from the alcohol, was pyriform in 

 general form (Fig. 19) and somewhat flattened on two opposite sides, so that a cross 

 section would be elliptical rather than circular. Four well-marked ridges run 

 meridionally and are separated from each other by furrows. Upon sectioning this 

 egg it was found that these ridges are wings of the medullary tissue. The 

 cortical tissue of the furrows is especially loose, and hyphae from two opposite sides 

 seem to be bridging and filling in the furrows. But the important feature is, that the 

 outer surface of the cortical layer conforms to the ridged medullary surface to a much 

 greater degree than in later stages, thus indicating that the medullary layer has taken 

 the initiative in the disposition of the tissues of the egg. 



The question in regard to the arrangement in C. columnatus of the gelatinous layer 

 of the peridium in four masses — as in most cases — separated from each other throughout 

 by four plates of cortical tissue, may be answered by stating that it has resulted from the 

 extrusion of the medullary tissue along four longitudinal lines out into the cortical 

 region. Here the entering masses have broadened out in their peripheral portions so as 

 to crowd the cortical portions between the masses into narrow plates. The answer to 

 this question for Anthurus borealis is somewhat the same, but is complicated by the 

 generic differences between Clathrus and Anthurus. In C. columnatus the cortical plates 

 extend from the base to the apex of the sporophore, cutting off all direct connection of 

 one gelatinous mass with its neighbors. This indicates that the medullary extrusions 

 were strictly lateral. In A. borealis, it has been pointed out that the six cortical plates 

 do not extend to the apex of the sporophore, and that the six gelatinous masses are in 

 direct connection with each other above and also have radial connection with the 

 medullary tissue of the gleba along six lines (ii, Fig. 16). Such connections indicate 



