202 SUMMARY OF CURRENT RESEARCHES RELATING TO 



by Ostenfeld is merely a long account of his previously published work. 

 It concerns the immigration of a plankton diatom into quite a new area 

 within recent years. 



Fossil Diatoms.* — J. Heribaud has examined the diatoms of the 

 Travertin strata laid down by the mineral waters of Sainte Marguerite, in 

 Puy-de-D6me. He finds that the Travertin may be divided into three 

 zones, inferior, middle, and superior. The principal species of each zone 

 are enumerated, but the new species are left over for another and later 

 communication. More than eighty species were obtained, about a score 

 of which are new to the Massif Central, and about half a score new to 

 science. The author concludes with a short summary : — 1. From the 

 presence of numerous marine diatoms, in the lower Travertin, and from 

 the almost complete absence of these species in the actual waters, it may 

 be deduced that the waters of Sainte Marguerite must have been formerly 

 much more strongly mineral than they are at the present day ; their 

 salinity has been constantly decreasing from the lower to the upper zone. 

 2. From the absence of marine diatoms in the actual waters, and from 

 the presence, in the immediate neighbourhood of the mineral springs, of 

 a fairly large number of plants belonging exclusively to a marine flora, it 

 may be deduced that diatoms are more exacting, with respect to the 

 mineralisation of water, than are the higher plants. 3. The examination 

 of specimens taken at different levels allows the successive modifications 

 of the diatom-flora to be followed with great exactness, and since the 

 variations should correspond with those of the sabnity of the water, it 

 follows that a careful study of the Travertins would furnish exact in- 

 formation on the history of mineral springs. 



New Genus of Pleurococcaceae.f — W. Bialosuknia describes an alga 

 which he, with the help of Chodat, has isolated from Lecanora tartar w. 

 It forms the type of a new genus, and is called Diplosphsera Chodati. 

 Details are given as to the method of multiplication. The formation of 

 zoospores has not been observed. The alga was grown in various nutri- 

 tive solutions, which are described. 



Protococcaceae.J — G-. Guglielmetti begins a series of papers on the 

 algological flora of Italy, the first contribution of which deals with the 

 Protococcacere collected in and around Padua. Forty-five species are 

 enumerated, to many of which critical notes are appended. One species 

 and a few varieties are new. 



Astrocladium cerastioides.§— 0. Tschourina describes a new genus 

 of algai of which she has found one species in the duck-ponds of the Pare 

 de l'Ariana, near Geneva. It belongs to the family Palmellacege, and 

 may possibly be the same species as that described by Reinsch under the 

 name of Cerasterias raphidioides, but the drawings and description of the 

 latter are too incomplete to allow of certainty. The development and 

 mode of division of the new alga are described. 



* Comptes Rendus, cl. (1910) pp. 61-4. i 



t Bull. Soc. Bot. oeneve, ser. 2, i. (1909) pp. 101-4 (1 pi.). 



X Nuov. Notar., xxi. (1910) pp. 28-39. 



§ Bull. Soc. Bot. Geneve, ser. 2, i. (1909) pp. 98-101. 



