472 SUMMAEY OF CURRENT RESEARCHES RELATING TO 



microsomes are very small and indistinct. 12. The evolution of nucleus 

 and cytoplasm may have been as follows. At first the excess of food- 

 material elaborated by the pigment was stored in the plasmatic micro- 

 somes as a carbohydrate — cyanophycin. Later the reserve in the central 

 region became more complex, and the proteid metachromatin granules 

 were formed. In time, the accumulation of nucleo-protein became 

 restricted to a very limited area in the cell, so as to ensure its equal 

 distribution after cell-division ; and this restriction only occurred on 

 division, as in Merismopedia. Thus part of the cell became physio- 

 logically and morphologically separated by its function during cell- 

 division, and it may be styled the " nucleus." At a later stage the 

 ■" nucleus " became stable and persistent, as in Chroococcus macrococcus. 

 The ground-substance also altered in character, forming a definite 

 cytoplasm. 



New Protococcaceae. — W. Conrad* describes and figures the type of 

 a new genus of Euprotococcacere, Errerella bornhemiensis, which is allied 

 to Golerikinia, Lagerheimia, Ghodatella, and Richteriella. It was found in 

 August 1913 in a haul made at Bornhem from the " Vieil-Escaut." 



H. Kufferath f describes a new species of Protococcacese, Cklorella 

 Juteo-viridis Chodat, with a var. lidescens. His paper consists of a study 

 of its physiology. 



Structure of Diatoms. J — N. E. Brown publishes notes on the 

 structure of the following species of diatoms : Pinnularia sp., Pleuro- 

 sigma balticum, P. angulatum, Surirella gemma, Xavicula serians, 

 Nitzschia scalaris, Amphipleura Lindheimeri, Coscinodiscus heliozoides, 

 Stauroneis phmnicenteron, and Triceratium favus. He describes in detail 

 his observations on the different species, and concludes that we can no 

 longer regard all the black dots usually seen upon diatoms as being 

 pores through the shell, although there may be cases where they are so ; 

 for in the cases examined they are certainly nothing more than light 

 effects or shadows. These are caused in Pleurosigma by the nodes of 

 the grating structure ; in Stauroneis by the membrane closing the meshes 

 of the grating ; in Triceratium by the membrane closing the pits in the 

 cell-wall. The author considers that the true pores must be sought in 

 the thin membrane of silex closing the meshes or pits. That diatoms 

 have pores is beyond doubt in the author's opinion ; also that some 

 voluntary extrusion of motile living matter from the interior to the 

 exterior of the diatom takes place. The pores are extremely minute. 

 The method necessary for detecting them is described. 



Coscinodiscus oculus-Iridis.§ - J. Pavillard publishes some observa- 

 tions on Coscinodiscus ocuh/s-Iridis, which is characteristic of the winter 

 plankton of the Mediterranean. He describes the structure of the 

 diatom, the formation of auxospores, and the formation of microspores 



* Bull. Soc. Roy. Bot. Belg., lii. (1913) pp. 237-42 (3 figs.). 



t Rec. Inst. Bot. Leo Errera, ix. (1913) pp. 113-320 (4 pis. and 28 figs.). 



1 Journ. Quekett Micr. Club, xii. (1914) pp. 317-38 (1 pi.). 



§ Bull. Soc. Bot. France, lxi. (1914) pp. 164-72 (2 figs.). 



