4io BOTANICAL GAZETTE [November 



leading up to the formation of the spore mother cells and elaters; 

 and Kienitz-Gerloff (23), in discussing the Jungermanniales, 

 adds nothing of importance. While a great deal has been written 

 on the mitoses in the spore mother cell, literature on the formation 

 of the mother cell is strikingly scanty. LeClerc du Sablon (25) 

 has made some important observations. He carefully investigated 

 the development of the sporophyte of Frullania dilata, and with 



I 



that species he compared Scapania compacta, Pellia epiphylla, 

 Aneura pinguis, Targionia hypophylla, and Sphaerocarpus terrestris. 

 He emphasizes some important points, namely, that there is an 

 early differentiation between elaters and spore-producing tissue; 

 that the elater is the equivalent of a row of mother cells; and that 

 the walls between spore mother cells and elaters early become 

 gelatinized. In the following statement he considers the irregu- 

 larity of the potential spore mother cells, but does not seem to 

 consider this feature of any importance. 



Tandis que certaines masses protoplasmic (s) destinees a devenir cellules- 

 meres de spores s'accroissent regulierement sur tout leur pourtour et presentent 

 raspect d'amibes a peu pres isodiametriques d'autres (el) s'allongent exclusive- 

 ment dans une direction, et acquierent la forme se produit cet accroissment 

 rapide, si c'est par formation de cellules nouvelles, ou par Telongation des 

 cellules deja existantes. 



Again he says (25, p. 169): 



Les cellules-meres continent a s'accroitre pendant longtemps encore, puis 

 on voit apparaitre a leur surface de petits silions, premier indice d'une division 

 en quatre spores. Pendant que ces silions se creusent et accusent ainsi de plus 

 en plus la forme de tetrade que prend la cellule, le noyau se divise en quatre, 

 puis le protoplasma se divise de meme, et a partir de ce moment on peut dire 

 que la division de la cellule-mere en quatre spores est consommee, les phe- 

 nomenes qu'on observe ensuite etant d'un ordre tout a fait accessoire. 



Campbell (4, p. 1 1 1) does not agree with LeClerc du Sablon's 

 observations on the disappearance of the walls in the sporogenous 

 tissue, and in this connection he makes the following statement: 



A great many carefully stained microtome sections of a large number of 

 liverworts belonging to all the principal groups have been examined by me and 

 invariably the presence of a definite cell wall could be demonstrated at all 

 stages. f 



