484 SUMMARY OF CURRENT RESEARCHES RELATING TO 



CRYPTOGAMS. 



Pteridophyta. 

 (3y A. Gbpp, M.A. F.L.S.) 



Prothallia of Ophioglossum vulg-atum.* — Xorma E. PfeifFer gives 

 an account of the prothallia of Ophioi/lossum vulgahim. These were 

 first discovered in I'.XU, in the Thuringian Forest by Bruchmaun, who 

 during five months succeeded in isolating 70 young examples. A similar 

 find is now recorded near Chicago. Where the grass has been burned 

 off, the mature Ophiof/lossum plants are very evident ; and where the 

 ground is very sbaded, Selajjhiella apus and Aneura pinnuis occur ; for 

 the spot is low and wet, and after inundation may harbour Riccia 

 Jiuitans. The spikes shed their spores in July; and it is suggested 

 that spore-germination depends on inundation. The prothallia so far 

 found have sporophytes attached to them ; and from the age of the 

 sporophytes it is evident that the attachment has persisted for some 

 seasons since fertilization occurred. The appearance of the prothallia 

 agrees with Bruchmann's description. The surface is uneven and 

 brownish ; the end is rounded or even tuberous ; the long axis is 

 vertical. Several sex organs are dotted over the surface ; production 

 of them was probably continued after fertilization. The central region 

 contains stores of starch, and is free from fungi ; but fungi abound 

 in four to six subcortical layers. Reproduction of Ophioglossum by 

 vegetative method is far more common than by gametophyte formation. 



Acrostichese and their Position in the Fern System, f — 

 G. Schumann writes on the position of the Acrostichea^ in the Fern 

 system, and is of opinion that they branch off from forms in which 

 the sporangia follows the course of the veins. The proof of this was 

 obtained by a study of early stages of development in which the 

 sporangia first appear above the veins. A further proof is seen in the 

 frequent transition -forms, in which also the sporangia follow the course 

 of the veins. Since the sporangia have repeatedly spread over from the 

 veins on to the parenchyma, the AcrostichejB must be broken up and 

 allotted different positions in the Fern system. Acrostichum aureimi 

 stands quite isolated both as to sporophyte and gametophyte. Perhaps 

 it should be placed near Fteris. Stenochlsena is allied to Blechnum. 

 The Leptochileaj with divided lamina branch off from Dryopteris, sub- 

 genus Meniscium ; those with undivided lamina probably from species 

 of Polypodium. Stenosemia may be left for the present in Pohjbotrya. 

 The green sporangia in Stenosemia and Leptochilus cuspidatus show that 

 the stem of the sporangium, and perhaps also the wall-cells, belong to 

 the tissue of the leaf. Further details must be sought in the original 

 paper. 



* Bot. Gaz., Ixi. (1916) pp. 518-22 (figs.). 



t Flora, cviii. (1915) pp. 201-60 (41 figs.). See also Bot. Centralbl., cxxxi. 

 (1916) p. 624. 



