452 BOTANICAL GAZETTE [jtjne 



i or 2. These are certainly nuclei and not pyrenoids, since they 

 were clearly distinguished by hematoxylin, safranin, or methyl 

 green. Many of these cells are somewhat vacuolated, and none 

 of them contains protein granules or visible chroma tophores. No 

 cases have been observed in which any of these cells are escaping 

 from the cavity. It seems probable from all the evidence available 

 that such a group as 3 is formed by division of the spores of a normal 

 cystocarp, and 2 is an intermediate stage between 1 and 3. Each 

 of these groups of multinucleate cells, therefore, is the product of 

 an abnormal cystocarp. 



Germination of the carpospores may begin long before they 

 escape from the thallus. The first step in germination is the forma- 

 tion of a gelatinous wall 2 \x thick (fig. 72). The chromatophores 

 in these spores were 3 /x in diameter and stained darkly. They are 

 similar in structure to those in the tetraspore, but are larger and 

 more openly clathrate (figs. 73, 74). The chromatophores are not 

 merely peripheral, but, as in the younger carpospores, are scattered 

 throughout the whole protoplast. The next step in germination 

 is the elongation of the spore until it becomes somewhat pear- 

 shaped (fig. 74). The nucleus then divides and the first cell wall 

 is formed perpendicular to the longitudinal axis of the carpospore 

 (fig- 75)- The narrow cell, as in the germinating spores of Fucus, 

 is destined to form the basal part of the young plant. Neither 

 growth nor cell division takes place as rapidly here as in the upper 

 cells. The next wall formed apparently divides the upper cell 

 obliquely (fig. 76). In a longitudinal section of an older sporeling 

 these two upper cells were divided into 9 cells and the lower cell 

 into 3 cells. All the cells of these germinating carpospores are 

 rich in cytoplasm and contain chromatophores- The maximum 

 size of the sporelings examined was 235 /x by 123 /x. In cavities 

 containing germinating carpospores traces of disintegrating cyto- 

 plasm and nuclei have been observed, showing that some of the 

 unicellular carpospores have degenerated. 



CYTOLOGY 



The nuclei in the auxiliary cell and the carpogonial branches are 

 the most satisfactory ones in the cystocarpic plants for the study of 



