84 Morphologie, Teratologie, Befruchtung, Cytologie. 



of the epimatium which is thus regarded as an axillary structure 

 exactly homologous with the ovuliferous scale of the Abietineae. 



Certain resemblances between the sub-genus Stachycarpus of 

 Podocarpus and Cephaloiaxits are regarded by the author as sug- 

 gesting that the Taxineae have arisen from some ancient member 

 of the Podocarpineae. Agnes Arber (Cambridge) 



Walker, N., On Abnormal cell-fusion in the Archegonium; 

 and on Spermatogenesis in Polytrichutn. (Ann. Bot. XXVII. 

 p. 115-132. 2 pl. 1913.) 



The reinvestigation of the sexual process and spermatogenesis 

 in Polytrichum was undertaken in order to check the remarkable 

 results obtained by J. and W. van Leeuw en-Reijnvaan published 

 in 1901. The present account differs in many respects from that of 

 these authors. 



In Polytrichum formosum no fusion was observed to take place 

 between the egg-cell and the large ventral canal cell. The fusion 

 appearances described by J. and W. van Leeuwen-Reijnvaan are 

 probably due to their method of preparation of the material. The 

 number of chromosomes in the spermatogenic cells is six and there 

 is so reduction during their last division. Centrosome like bodies 

 occupy the poles of the spindle during the last division, but are 

 not present during the earlier divisions. The centrosome-like par- 

 ticle persists in the spermatid and becomes the blepharoplast. The 

 greater part of the chromatin of the spermatid passes from the 

 nucleus into the cytoplasm and collects in the form of two spherical 

 roasses. An arched band-like organ is next developed, probably at 

 the expense of the extruded chromatin bodies, one of which is con- 

 sumed in the process. This band passes round the periphery of the 

 spermatid and joins the blepharoplast, thus connecting this body 

 with the remaining mass of chromatin. The nucleus of the sper- 

 matid becomes drawn out along the arched band and the greater 

 part of the latter is re-absorbed by the nucleus. In the presence of 

 water, the ripe antheridium extrudes a mucilaginous mass, in which 

 the spermatozoids are imprisoned. Each spermatozoid rapidly revol- 

 ves within a spherical vesicle. An interesting series of experiments 

 is described, bearing upon the escape of spermatozoids. It is shown 

 that under favourable conditions an enormous number of spermato- 

 zoids is extruded from the antheridium of each rosette and a great 

 wastage must result through the dißiculty of their escape from the 

 vesicles. It is suggested that possibly only the most vigorous speci- 

 mens are thus selected for the Operation of fertilization. 



Agnes Arber (Cambridge). 



Woodburn, W. L., Spermatogenesis in Plasia pusilla, L. (Ann. 

 Bot. XXVII. p. 93-101. 1 pl. 1913.) 



Antheridial plants of Plasia pusilla were fixed in chroraic- 

 osmic-acetic acid at intervals during the month of July. 



The mitotic stages in the spermogenous tissue show no indica- 

 tions of centrosomes. An individual membrane surrounds each 

 member of the pairs of spermatids produced, but no wall separates 

 the two. 



The blepharoplast makes its appearance first as a dense area of 



