282 



nnco of siich ;i hoiiy »is Ihe herald of every local develoj^incnl». 

 Hor: has uiilcrlakcMi lo sliuiy Ihe orii^in of Ihese hodies. Slie says 

 Ihal oiie end cell »lakes oii a heavy mucilage coal»; Ihis is Ihe 

 only fealure by which it can be dislinguished fioiii olher cells or 

 from young hairs. Like lliein il divides and forms a shorl cell 

 row ; bul apparenlly Ihis is not ils only mode of origin, for in (ig. 

 14 RoE presents »two initial rows which are modiiied young hairs» ; 

 fig. 11 shows a pear-shaped body tcrminaled by a typical hair; 

 in fig. 8 the inilial is borne by a cell row which in no way differs 

 from others in this region, and, linally, in fig. 9 is an inilial cell 



situaled laterally on a liair high 

 above ils base. All the cross walls 

 in the »inilial row> are Ihen 

 resorbed and the nuclei dis- 

 appear. The terminal part rc- 

 lains ils shape and becomes the 

 pear-shaped head, while the 

 lower part becomes filiform 

 from pressure; this is the laillike 

 appendnge wilh a narrow, some- 

 times almost invisible lumen. 

 Thus, Ihe initial is Iransformed 

 in lo the mature slructure as 

 described by Mitchell and 

 Whitting. 



If Roe's observations are accu 

 råte, Ihere is nolhing in the 

 Avhole class of brown algae thal 

 presents the slightest likeness 

 lo this peculiar slructure. Hav- 

 ing some general idea of the 

 group, I underlook lo sludy the apical region of Splachnidinm in 

 some detail. Years ago I made microlome sections of the 1908 

 material; this being ralher advanced (almost without hairs) I made 

 numerous hand seclions of the new material while Professor 

 O. JuEL kindly prepared the microlome seclions for which I tender 

 him my best thanks. The sludy of Splachnidinm was finished in 

 the Jodrell Laboratory of Kew, and I thank the Keeper, Mr. 

 BooDLE, for kind assislance. 



I am unable to confirm Roe's stalemenls. I have studied nume- 



Fig. 3. a, b. »luitials» in the growth- 



zone, X c. 400. c. i» Initial > penetrating 



olcler cortex, X c. 400. 



