164 I I! E JOL' li\"A I, OF HOTAM' 



Stem terete, thread-like, branched, with internodes and anatomy 

 as in P. pusillus. Loaves of thin texture, soft, light green in colour — 

 reddish or brown in older leaves— pellucid, 3-nerved with lacuna; on 

 either side of tbe midrib and lateral nerves near the margin, slightly 

 narrowed below, not tapering above, apex very rounded-obtuse — 

 usually more so than in I\ dbtusifolius. Ligules open and convolute. 

 Peduncles slender, short, ± 24 mm., with small few-flowered spikes 

 (2-3 mm.) — only seen once (Esthwaite) during an abnormally hot 

 summer. Mature fruit not produced ; propagating by winter-buds. 

 Occurs in Windermere, Coniston, Esthwaite, Derwentwater, Bassen- 

 thwaite, Ullswater, Crummock, Buttermere, Ennerdale, Wastwater, 

 and Hawes Water, upon finer and more fertile soils than P. pusillus 

 and under a light-intensity of 10-2 %» at depths varying from 

 5-8 ft. (Esthwaite) to 20 ft. in lakes with clearer water (Ullswater). 

 Of the stations recorded in this preliminary paper, those in Wast- 

 water, Ennerdale, Crummock, Buttermere, and Derwentwater are in 

 Cumberland, v.c. 70 ; Hawes Water is in Westmoreland, v.c. 69 a ; 

 Windermere, Coniston, and Esthwaite Water are in N. Lanes., 

 v.c. 69 b ; and Hawes Water, Silverdale, in W. Lanes., v.c. 60. 

 Stations in Ullswater are in both 69 a and 70. All other waters 

 cited are in N. Lanes. 



(To be continued.) 



THE LICHEN LIFE-CYCLE. 

 By A. H. Church. 



(Continued from p. 145.) 



III. The Lichen. 



The more generalized scheme of Ascomycete progression is 

 considerably amplified by the story of the Lichen. In spite of 

 intrusive algal protoplasts now exploited as a convenient source 

 of carbohydrate, the thallus is still little more than that of a 

 skinned sea-weed with no superficial tissue of an older order as 

 photosynthetic ramalia or cortex, or even superficial reproductive 

 ramuli ; however much the growth-form and ramification of older 

 marine somata may continue in operation with the new investment of 

 algal ' gonidia ' (cf. Gladonia, Ramalina, Usnea, Dactylina). In 

 many cases the reproductive mechanism is much more definite. The 

 anth'eridial ramuli are absfricted in minute conidial form, as so- 

 called 'spermatia.' Algal zo'idogamy is replaced by spermatogamy l , 

 instead of by the siphon ogamic approximation suggested by Pyronema 

 and Sphcerotheca, Cross-fertilization may be still procurable in an 

 open medium : water-carriage of the minute spermatia remains pre- 

 dominant; air-carriage is doubtful and wholly unproven. The re- 

 productive ramulus of the megagamelangium is not at all oogonium- 

 like where known (Collema, Physcia, Usnea), but ends in a uni- 

 seriate ramulus of cell-organization quite distinct from that of the 



1 ' Spermatogamy ' as applied to the method of conjugation in the Floridea3, 

 in which such phenomena were first clearly described by Bornet and Thuret 

 (1867). The word is open to the objection that it is too suggestive of Seed 

 Tlants ( Sperm atop hyta), and of fertilization by a ' sperm ' ; but with its present 

 suffix it is the only readily intelligible correlative of zoidogamy and siphonogamy. 



