373 WILLIAM ARCHER. 



Palmellaceous or Chroococcaceous, are prone to be more or 

 less permeated by " myceloid " threads, and even some snch 

 as would fairly well accord with those Reess depicts for 

 Collema, though not so copiously branched, may not be 

 unusual. Some of these threads are, at least occasionally, 

 those of indubitable (devasting) fungi, which, when they 

 "' attack " certain cells, destroy them ; other threads, doubt- 

 less quite distinct, can apparently live independently and 

 innocuously, though probably drawing nutriment from the 

 common mucous matrix. What a monstrous and abnormal 

 "^ Lichen-thallus " thus not unfrequently comes to view — a 

 variable "hypha" interruptedly running hither and thither, 

 and accompanied by " gonidia " of very heterogeneous 

 character ! The plant named by Klitzing Trichodictyon 

 rupestre,vf\\\Qh can hardly be doubted to be the same as Cylin' 

 drocystis crassa, De Bary, is frequently (though not always) 

 accompanied by a number of fine filaments (which seem, 

 however, to be inarticulate), twisted in and out through the 

 gelatinous mass made by the alga, but so running as to leave 

 rounded spaces between, containing the groups of the 

 Cylindrocystis-cells ; they seem, in fact, to urge their way 

 between the more dense mucous envelopes formed round the 

 groups of dividing cells, simply because they find the intervals, 

 being softer, more readily permeable. These filaments, 

 whatever their nature really may be, cannot be doubted, I 

 should think, to be foreign, though they Avere introduced 

 into the generic characters by Klitzing, being considered by 

 him as somehow a portion of the structure of the alga, which, 

 indeed, itself reproduces by conjugation, and is, no doubt, in 

 fact, a desmid. 



Schwendener claims as the foundation or basis for the 

 production of '' Collemaceee " only such nostochaceous plants 

 as live in moist or wet habitats — the entirely aquatic forms 

 (Trichormus, Sjihoerozyga, Cylindrospermum, Dolichosper- 

 mum), he considers, being inaccessible under water, are 

 protected from the attack of the parasite, and thus " cannot 

 enter into the ' gonidia question.' " The fact that these latter 

 form independent " spore- cells " (reproducing the plant), he 

 would seem, so far as we can judge, to hold as having no 

 material, if any, bearing on the question, for he dwells only 

 on their being submerged as giving them an immunity. 

 " But in any case," he says, afterwards, further on, as regards 

 the question, " Avhether certain species of Cylindrospermum 

 pass into the ' gonidia state ' [that is, become the basis of 

 Collemacete] remains for so long doubtful, till the transition, 

 here alone decisive, be observed. In the Collema-thallus 



