ZOOLOGY AND BOTANY. MICROSCOPY, ETC. 221 



Flora." The gemmae of a specimen of Tortula mutica from North Wales 

 are now described. They were found scattered over the upper surface of 

 the leaves, and also rarely on the protonema. They consist usually of 

 two or four cells, bounded by thick, reddish-brown walls ; they are easily 

 detached and are capable of resting ungerminated. In an allied specie?, 

 T. impillosa, gernm^ occur only on the upper part of the thickened leaf- 

 costa. A. G. 



Rhaphidostegium coespitosum (Sw.) and its Affinities.— H. N. 

 Dixon {Joum. of Bot., 1020, 58, 81-9). An account of the investi- 

 gation of numerous original specimens collected in various countries, and 

 described as species by a large number of authors. It is found to be 

 quite impossible to maintain them as distinct species ; they show them- 

 selves inevitably to be but forms of one species widely spread throughout 

 the tropical and subtropical regions of the southern hemisphere, and 

 extending also into the temperate zone. The oldest type is Hypnum 

 coespitosum Swartz (Prodomus, p. 142 [1788]), placed in /?^«/;M^os^e^mm 

 by Jaeger, and now furnished with a synonymy running to nearly three 

 score names. This is one of the most extensive and satisfactory reduc- 

 tions of unnecessary and redundant species that has yet been achieved 

 in bryology. A. G. 



Thallophyta. 



Algae. 



Attempt to explain the Colourless Series of Flagellates. — A. 

 Pascher {Ber, Deutsch. Bot. GeselL, 1916, 34, 410-7 ; see also Bot 

 Centralbl, 1918, 137, 20-22). A synopsis of the lines followed by 

 the author in his treatment of the fresh-water flagellates in Rabenhorst's 

 " Kryptogamen Flora." He considers that the colourless forms which 

 occur in every series of coloured flagellates are a secondary development 

 of the coloured forms. In every colourless series there are genera and 

 species which stand in the closest relation to the coloured ones, but with 

 a reduced chromatophore apparatus, and having a saprophytic, parasitic, 

 and animal existence, thereby declaring their derived character. Inter- 

 mediate stages are found ; and it is possible artificially to produce 

 colourless from coloured forms. In all the coloured series animal 

 nutrition occurs secondarily, and leads direct in certain forms to a per- 

 manent rhizopodial organization. As opposed to the coloured series of 

 flagellates, there are three series of 'colourless forms, with characters 

 which, among coloured flagellates, are only found in derived forms. The 

 author considers Protomastiginse and Pantostomatin^ to be series of 

 flagellates which have been classed together on quite secondary charac- 

 ters, and therefore represent wholly artificial, heterogeneous, polyphyletic 

 groups. The component species are apochromatic and apoplastid forms 

 of the most diverse coloured species, and in some cases are so obviously 

 related that the coloured and colourless should not be separated. The 

 author only continues the present artificial classification for the sake of 

 convenience. He gives an enumeration of the coloured and colourless 

 series. E. S. Gepp. 



