100 SUMMARY OF CURRENT RESEARCHES RELATING TO 



relations of the cells in a colony in order to cast light upon the inter- 

 actions of cells, and their influence in heredity and ontogeny. In 

 general, the colonies consist of sixteen cells, forming a square with trun- 

 cated corners, somewhat octagonal in outline. It is shown that the 

 eight cells making the corners of the square are in contact each with 

 three cells, the middle cell of each is in contact with four, and each of 

 the four interior cells is in contact with six cells — thus the series of 

 curves described by Cohn are brought about. It is fundamental that 

 the successive planes of division intersect- at right angles. The colony 

 organization, in short, corresponds to the type of division involved in 

 the formation of the cells. It follows that the colony form is not 

 dominant in determining the division planes in new colony formation ; 

 that is, " cellular organization " is important, and not heredity of form 

 for the whole organism. Undoubtedly the readjustments in the posi- 

 tions of the cells with the growth of the colony are towards stability and 

 compactness. That the colonies are under considerable pressures as 

 between the different parts is shown by their behaviour. Regeneration 

 of injured cells does not occur. 



Concretious formed by Aigge.* — H. J. Roddy writes on concre- 

 tions in streams formed by the agency of Blue-green algse and related 

 plants. He describes concretionary formations occurring in Little 

 Conestoga Creek, Lancaster County, Pa., U.S.A. He discusses their 

 size, shape, composition, hardness, structure and origin ; and gives 

 evidences that the active agents of these concretionary formations are 

 Blue-green algje. Species of the genera Gleoatpsa, Ghothece, Apluino- 

 capsa, Nostoc, OsciHatoria, and Rivt'Jaria liave been identified. Associated 

 with these are several of the Chlorophycete. Many species of the 

 Diatomacefe and Desmidiacea which generally live in close association 

 with Cyanophyceae have also been identified, and have, no doubt, con- 

 tributed the siHceous matter which is disseminated through the calcareous 

 matrix. Species of Navkuhi are prominent. The author was successful 

 in finding a still greater abundance of concretionary formations in 

 Donegal Creek, Lancaster County. The species associated with them 

 include Microcystis, Coilospherium, and Chroococcus, besides most of those 

 already mentioned above. There are also species of Frotococcus, Diatoms, 

 Desmids, Chloropiiyccc'e, Ph^ophyceee, and RhodophyceaB. 



Bohemian Characese.t — J. Wilhelm writes on the Characese of 

 Bohemia. Of the fifty to sixty European species, the author records 

 twenty-four for that country, of which three are new to Bohemia and 

 three are new species. Many new forms and varieties are also described. 

 Fear is expressed that, owing to the extensive draining and cultivation 

 of the land, many species will be permanently lost. 



The Characese of France. J — F, Hy publishes an additional note on 

 the Characea? of France, in which he mentions a great number of 



* Proc. Amer. Philosoph. Soc. Philadelphia, liv. (1915) pp. 246-58 (figs.). 



t Vestuik V. sjez. ces. prir. (1915) p. 333. See also Bot. Centralbl., cxxix. (1915) 

 p. 379. 



X Bull. Soc. Bot. France, Ixi. (1914) pp. 235-41. See also Bot. Centralbl. , cxxix. 

 (1915) p. 62. 



