212 SUMMARY OF CURRENT RESEARCHES RELATING TO 



■cellulose at first, and later resembles fungus-cellulose. The cell- wall is 

 laid down as microsomata, in lamellae on the inside of the cell-wall. A 

 long bibliography is appended. 



Phytoplankton of Donjec.* — L. Reinhard has made a study of the 

 phytoplankton of the Donjec, and finds that the forms which are 

 characteristic of larger rivers are for the greater part wanting there, 

 Melo&vra granulata being almost the only exception. On the other hand, 

 the flora is rich in Limno- and Heleoplankton forms, as Volvocinese, 

 Pediastrum, Scenedesmus, etc. This is attributed to the fact that the 

 Donjec is rich in bays which penetrate far into the land, and attain the 

 character of closed basins. In these the plankton is developed, and 

 floats thence into the main stream. The number of species found in a 

 short stretch of the river during a month's work was 135. 



Clementsia Markhamiana.f — 0. Murray gives the following de- 

 seription of this new pelagic genus and species : — " Units existing in 

 colonies within a stratified integument, dividing into groups of four, 

 varying much in the numbers of the colony ; the integument gradually 

 growing in thickness and in stratification ; ultimately bursting and per- 

 mitting the escape of the unit cells ; unit cells increasing in size 

 markedly and (presumably) subdividing into colonies like the parent 

 colony ; in nearly every stage characterised by the thick and many times 

 stratified walls of the integument, and especially also by the abundant 

 oily and chlorophyllaceous contents of the cells." It was collected in 

 the Atlantic a few degrees south of the Equator during the outward 

 voyage of the Discover//. Four stages in its life-history are figured in 

 colours. The data given are strongly suggestive of Glceocystis, but the 

 affinities are not stated. 



Division in Desmids under Pathologic Conditions.! — J. A. Cush- 

 man has examined species of Cosmarium, Euastrum and Micrasterias, in 

 which the process of division was taking place in the digestive tract of 

 certain Entomostraca. The newly-formed cells are contorted, and quite 

 unlike the species. A figure is given of a species of Micrasterias, 

 showing two quite dissimilar semi-cells. 



Penicillus and Rhipocephalus.§ — A. and E. S. Gepp describe two 

 novelties — Penicillus pyriformis and P. Lamourouxii Decaisne var. 

 gracilis — both collected in the West Indies by Mr. M. A. Howe. 

 P. pyriformis differs from the common species, P. capilatus, in having 

 a pear-shaped capitulum composed of interlacing filaments ; the stalk 

 barely penetrates into the head. The new variety of P. Lamourouxii is 

 intermediate between that species and P. capitatus. It closely resembles 

 P. Lamourouxii in habit, as also in its thin-walled, compressible, usually 

 flattened stem, which penetrates but a very short way into the capitulum. 

 It differs from P. capitatus in having coarser filaments and a soft com- 

 pressed stem, not nearly penetrating to the middle of the capitulum. 

 The unicellular character of both Penicillus and Rhipocepihalus is insisted 



* Arb. Nat.-forsch.Gesell. Univ. Charkow, xxxix. (1904). 



+ Geogr. Joum., xxv. (19U5) pp. 121-3 (1 pi.). 



J Rhodora, vi. (1904) p. 234. § Journ. Bot., xliii. (1905) pp. 1-5 (1 pi.). 



