I9 K,] WE—CONCEPTACLE IN FUCUS 241 



if the species happens not to be monoecious. Immediately upon 

 loss of the fragile hairs described in the foregoing, or from basal 

 portions which failed to develop them, new papillae develop which 

 by their subsequent behavior indicate whether antheridia or oogonia 

 are to come. In the former case, segmentation may continue until 

 an elaborately branched and complicated structure bearing numer- 

 ous antheridia is formed. In case of formation of oogonia, the 

 papillae segment once, cutting off the pedicels and oogonia proper 

 (fig. 20). Further development up to blocking off of 8 eggs (fig. 20) 

 is as already described by many writers (Farmer and Williams 9, 

 Oltmanns 19 and 20, Strasburger 28, Yamanouchi 30, Simons 

 27, and others). 



In Splachnidium rugosum the cavity is initiated by disintegration 

 of an entire row of the thallus (and a terminal hair as well in some 

 cases), pressure of active cells on each side reducing the disinte- 

 grating row to a long filiform structure which is left free subse- 

 quently by withdrawal of abutting cortical tissue in its effort to 

 keep pace with active tissue toward the exterior. The abutting 

 tissue at the external surface continues division and active growth, 

 leaving the original initial row in a depression. Reproductive 

 organs succeed a loss of hairs in the pit, just as in Fucus, except 

 that here there are no evident antheridia or oogonia, but merely 

 reproductive sacs. 



Examination of Hormosira and Sargassum material seems to 

 show the same behavior. 



Discussion 



It will be noted from the foregoing description that the sex 

 organs appear after maturity of the hairpit, and, moreover, they 

 appear in the hairpit itself. In other words, the hairpits and the 

 conceptacles are certainly homologous structures, as already 

 admitted by many, since one, the hairpit, is the juvenile stage of the 

 other, the conceptacle. All hairpits, therefore, are potentially capable 

 of proditeing reproductive organs. 



Moreover, sex organs have actually been seen in hairpits, de- 

 scribed by Simons (27) as a "peculiar condition" (p. 173). She 

 finds papillae and stalked cells like those which precede male 



