BOOK -NOTES, NEWS, ETC. S7 



(2; Dwarf Habit, (3) Absence of Attachment Disc, (-Ij Spirality or 

 Curling of the thallus. The methods of investigation employed by 

 the authors show that Dwarf Habit is due to prolonged exposure to 

 the air and diminished immersion in the water; that Curling or 

 Spiralit}^ is probably due to an unequal distribution of water and 

 nutrient salts upon tlie thallus as it lies spread out on the intertidal 

 mud ; that Vegetative Reproduction is probably favoured by the 

 constant humidity of the intertidal mud, thus preventing that con- 

 centration of cell-sap which is necessary as a stimulus for the 

 production of receptacles and for the maturing of sexual organs. The 

 species to which most of the marsh ecads are traced is Fncus 

 vesiculosus. The authors add that "an examination of the famous 

 floating Sargasso weed revealed the interesting fact, that its pecu- 

 liarities could be referred to the same ])hysical factors as those of 

 the marsh Fucoids — a confirmation of Borgesen's contention that it 

 is produced and reproduced Negetatively from one of the saxicolous 

 Sargassums.'' — A. (i. 



The Twenfy-frsf Arniiial Report of the 3Ioi<s Exchaiif/e Chih 

 (York : printed by Coultas k Volans, Ltd. April 1916, pp. 145-176), 

 issued by Mr. W. Ingham, Hon. Secretary, contains a statement by 

 the Distributer, Mr. P. G. M. Khodes, that an exceptionally large 

 number of critical and off-type specimens had been sent in by the 

 members, thus throwing more work upon the referees, whose criticisms, 

 are accordingly the more valuable and interesting and do much towards 

 the elucidation of difficult forms. The notes under Spliagniun suh- 

 seciindum, Foniinalis antipj/retica, Plagiotheciiim BoesecnntDi, certain 

 harpidioid species oi Ili/puinn, and Hijpinim pahistre var. suhsplicrro- 

 carpnim, are of special interest. The last named variety has given- 

 great trouble to our bryologists. The British plants referred to it 

 differ from the Pyrenean type in shape of capsule, and consequently 

 need a distinctive name ; this is supplied in the appendix — Hypniiin 

 palustre var. doJichonf iiron Ingh. Si Rhodes. — A. G. 



At the meeting of the Linnean Society on 18th January, Professor 

 F. O. Bower, vSc.D., F.R.S., F.L.S., gave a lecture on " The Morphology 

 of the Sorus of Ferns,'' the fcdlowing iheses being maintained and illus- 

 trated in a long series of lantern-slides of living and fossil species : — 

 1. The isolated sporangium (monangial sorus of Prantl) is frequent 

 among primitive Filicales. 2. The distal or marginal position of the 

 sorus is prevalent in primitive types. 3. The transition from a marginal 

 to a superficial position has frequently occurred. 4. Interjiolation of 

 sporangia has led to increased complexit}^ of the sorus. 5. In simple, 

 gradate, and mixed sori thus constituted the receptacle varies : it is 

 not a stable entity, but a result of elaboration of the vein-ending on 

 which the sporangia are seated. 6. Superficial extension of sori occurs 

 7. Duplication of sori also occurs. 8. Fusion of son also occurs pro- 

 gressively in various phyla. 9. The fusion-sorus may disintegrate, but 

 not necessarily along the original lines of fusion. 10. The identity^ of 

 the sorus may be lost by acrostichoid development, which has occurred 

 along numerous lines of phyleticadviince. 11. The more complex sori 



