46 "^'ûJ. XLIT[., Art. 1.— K. Yendo : 



whether Alarla sheds its blade periodically, for instance, appears 

 to me to be yet unsettled. 



The gametophyte stages of A. crassifoUa I have also studied 

 from living material collected in the field. Owing to a consider- 

 able number of strangers always associated with the sporelings of 

 the plant, it was not easy matter to trace the stages of develop- 

 ment in a satisfactory manner. The sterile fronds of 3Iicrosphar{?), 

 Myrionema and Edocarpus, which are found growing with the 

 sporelings, have been especially embarassing. Unfortunately I could 

 not find any sporophyte directly starting from a gametophyte. 



The earliest stage of development of the sporophyte which I 

 observed was two-celled (Plate XVIII, fig. 4). The lower cell was 

 cylindrical, measuring 8// in diameter about 2Gf^ in length with the 

 basal end slightly crooked. It had no special content except fine 

 granules and colourless plasma. The upper cell was similarly 

 cylindrical with roundish apex, and measured 9/^ in diameter, 2Q,u 

 in length. Disc-shaped chromoplasts compactly lined the inner 

 surface of the wall, and a few highly refracting grains were 

 present. In both cells the nuclei were not visible before staining. 

 As far as the blade is composed of a single layer of cells, the frond 

 in a more advanced stage is essentially similar to that of the cor- 

 responding stage I have observed in Costaria Turneri. 



In elucidating the development of Costarla Turneri and other 

 Laminariaceous plants, P) have pointed out that : — the growth of 

 the early embryonal, monostromatic fronds is mainly due to the 

 activity of the subapical cells, and that of the later polystromatic 

 fronds, to the activity of the transitional region. Killian's^) obser- 

 vation on the development of Laminaria dlgltata agrees with mine 



1) Yendo: Development of Costarla, etc., p. 713. 



2) KiLLiAN : Beitrüge zur Kenntn. der Laminarien, p. 447. 



