ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 187 



nucleolus shows no signs of disintegration until the increase in chromatic 

 material has come to an end. Centrosomes are not to be identified at 

 any stage of the nuclear division. Cell-division is accomplished by the 

 splitting of a granular cell-plate, which has been formed by the central 

 spindle. The splitting takes place from the centre outward. The 

 entire pyrenoid is segmented to form several starch-bodies. No differ- 

 entiated central area is present. 



Oocytis.* — H. Printz publishes a systematic synopsis of the genus 

 Oocystis. He describes the species fully, taking not only form and size 

 but also cell-contents into account. Fourteen species are fully known, 

 and diagnoses of another thirteen are incomplete. They probably 

 represent, however, good species. Nine species are doubtful and 

 probably worthless. The author discusses generally the cells, membrane, 

 chromatophores, and reproduction. 



Notes on Microscopic Algse.f — N. Wille continues his algological 

 notes : xxii-xxiv. In the first of these he clears up doubtful points 

 in certain genera of Algae by reference to the Agardh herbarium. The 

 genus Gloiodictyon was regarded as a " genus dubium " by Kiitzing, 

 ignored by Rabenhorst and revived by De Toni, who adds other species. 

 An examination of the type G. Blyttii Ag. shows that the alga is a 

 Zygnema sp. ; and the genus must therefore be dropped. Trypothallus 

 should perhaps be placed near Prasiola. Hsematococcus Noltii Ag. is 

 Euglma sanguinea, as has been suggested. Protococcus viridis Ag. is 

 identical with Plearococcus Naegelii Chod. The genus Gystococcus Naeg. 

 must be dropped in favour of Ghlorococcus Fries. Protococcus monas 

 Ag. is merely the young newly-formed autospores of Ghlorella elUpsoidea 

 Gern. Protococcus glomeratus Ag. must disappear as a name, since the 

 type material consists of a mixture of species. The unpublished species 

 P. salicis Ag. and Apiocystis Wilsoni Ag. resembles respectively Trente- 

 pohlia umbrina Born, and Isthmia membranacea CI. In note xxiii the 

 author gives further details of his Ulothrix subflaccida. He records 

 gametangia and gametse, and notes that the copulating garnetse are 

 fairly similar in size. In note xxiv, a new epiphytic Lyngbya, L. 

 epiphylica, is described. He calls attention to the fact that he had 

 previously sent a different species under this name growing on CEdo- 

 gonium sp. and Tolypothrix sp. to Professor Kirchner, who shortly 

 described it in Engler and Prantl's Pflanzenfamilien. 



Swedish Fresh-water Algae. $ — G. E. Cedergren publishes a list of 

 the fresh-water algae of Sweden, giving a synopsis of the principal algal 

 formations or associations as represented in the neighbourhood of Upsala. 

 The commonest type is the pond formation, divided into groups accord- 

 ing to external conditions, intensity of light, impurity of water, etc. 

 Another type is from ponds with clear spring water, which is very similar 

 to that from flowing and moving water, both being designated as philo- 

 kinetic. Sphagnophil algae, rain-water or ombrophil algas, rock-wall or 



* Nyt Mag. Naturvidensk, li. (1913) pp. 165-203 (3 pis.). 



t Nyt Mag. Naturvidensk, li. (1913) pp. 1-26 (1 pi.). 



J Arkiv f. Botanik, xiii., No 4 (1913) 43 pp. (figs, in text). 



