Morphologie und Teratologie. 3 



Beer, R., On the Development of the Spores of Riccia 

 glauca. (Annais of Botany. Vol. XX. 1906. p. 275—291. 

 With 2 piates.) 



The first division of the egg cell is obliquely transverse. Succe- 

 •ding divisions result in a inass of spore-mother cells which are at 

 first separated from each other by extremely delicate membranes in 

 which no cellulose was found. Secondary and tertiary thickening 

 are then deposited giving pectose cellulose reactions. The proto- 

 plast then rounds itself off and the secondary thickening layer, which 

 becomes mucilaginous either separates from the primary wall, forming 

 an externa! envelope, or, remaining partly adherent, becomes drawn 

 •out into Strands of mucilage between the primary wall and the tertiary 

 thickening layer. 



The resting nucleus of the spore-mother cell contains a large 

 nucleolus which consists of a number of deeply chromatic granules 

 embedded in a faintly staining matrix. There is a long and well 

 marked spireme thread in the prophase of the division; the reduced 

 number of chromosomes is seven or eight. The membrane formed 

 between the daughter cells does not reach to the periphery of the 

 cell, but at the close of the second maiotic division the special 

 mother cells are separated from one another by membranes com- 

 posed of pectose-cellulose. A secondary thickening layer of 

 cellose is then deposited on these special mother cell walls by the 

 protoplast. 



The first spore wall is a cuticularised structure from a very 

 early period. Within it at the equatorial rim is deposited a plug of 

 mucilage giving callose reactions but which has no direct relation 

 either to the thickening layers of the special mother cell or to the 

 first spore wall. It is a new and independant formation. The second 

 spore wall is formed within the first and is cuticularised. It at first 

 appears to be homogeneous, but later on it can be seen to consist 

 -of three parts: 



I an external loosely laminated region; 



II a layer of dark coloured material; 



III an internal densely laminated region. 



The endospore forms late and gives reactions for cellulose and 

 pectose. The protoplasm of the spore is actively concerned in the 

 ^rowth of the membranes which Surround it. There is an intimate 

 Union between each new lamella added to the wall and the proto- 

 plast, and the spirem-like structure of the spore nucleus suggests the 

 occurrence of active metabolic processes in the cell. The material 

 for the growth of the spore walls is derived partly from the breaking 

 down of the parietal cells of the sporangium and is probably 

 supplemented by material assimilated by the vegetative cells of the 

 thallus, which diffuses into the sporophyte. After the first spore 

 wall has been formed and during all earlier periods of the growth 

 of the second spore wall, a quantity of mucilage is present in the 

 -sporangium between the tetrads. M. Wilson (Glasgow), 



Robertson, A., Some Points in the Morphology of Phyllo- 

 cladus alpinus Hook. (Annais of Botany. Vol. XX. 1906. 

 p. 259—265. With 2 piates.) 



A description of the vegetative organs and male and female 

 ■cones is given. Centripetal xylem occurs in the cladode but is ab- 

 baut from the leaf, main axis and axis of the cones. It consists of 



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