Januaky 29, 1904.] 



SCIENCE. 



173 



temulentum, L. perenne and L. linicola, 

 one with and one without the fungus sym- 

 biont. Of these the with-fungus race is 

 the slightly more vigorous. Present 

 knowledge points to the probability that 

 the fungus is an Ustilagene, which has lost 

 its power of spore formation and has 

 adopted a method of intraseminal mycelial 

 infection at the first appearance of the 

 stem growing point. Infection of without- 

 fungus plants seems impossible, as is also 

 the elimination of the fungus from the 

 with-fungus plants. 



Mitotic Division of the Nuclei in the Cyan- 



ophycece: Edgar W. Olive. 



The 'central body' in the Cyanophycese 

 is a nucleus, not essentially different from 

 the nuclei of higher plants. When condi- 

 tions for growth are favorable, the vegeta- 

 tive cells divide with unparalleled rapidity, 

 so that their nuclei are rarely in a state of 

 rest. Consequently during this period of 

 mitotic division a nuclear membrane is not 

 present. In spores and heterocysts, on the 

 other hand, the nuclei form nuclear mem- 

 branes and they resemble, furthermore, in 

 other respects the resting nuclei of the 

 higher plants. When in division, the 'cen- 

 tral body' is made up, for the most part, 

 of a more or less dense kinoplasmic achro- 

 matic substance, which corresponds to the 

 spindle, and which is composed both of 

 mantle fibei's, attached to the partition 

 walls of the cell, and of connecting fibers. 

 The chromosomes, which can be success- 

 fully demonstrated only by careful differ- 

 entiation of stained material, are very 

 minute, and are usually sixteen in num- 

 ber. In the large species Oscillatoria prin- 

 ceps and 0. Froehlichii, however, there are 

 thirty- two, while in Nostoc commune and 

 in Gleoca2:)sa polydermatica there are but 

 eight chromosomes. In Gleocapsa the 

 plane of division of the chromosomes is 

 exceptional, in that it takes place at right 



angles to the resulting plane of division of 

 the cell. In all the other forms studied, 

 embracing five genera, the plane of divi- 

 sion of the chromosomes is normal, being 

 parallel to the resulting plane of division 

 of the cell. In the filamentous forms di- 

 vision of the cells takes place with wave- 

 like regularity; and in all cases studied, 

 with the exception of Gleocapsa, division 

 of the cell is accomplished by the growing 

 in from the peripheral wall of a ring- 

 formed wall. In Oscillatoria several ring- 

 shaped walls, in different stages of growth, 

 may be present at the same time in the 

 same cell, long before the one first formed 

 has completely divided the cell. Two 

 kinds of granular inclusions, which are 

 characteristic of the Cyanophycete, the 

 cyanophyein granules and the slime glob- 

 ules, or 'central granules,' are usually 

 present in the cytoplasm. The peripheral 

 position of the cytoplasm is generally dif- 

 ferentiated into a denser, fibrous region — 

 the chromatophore — which contains the 

 diffused gx-een and blue coloring matters. 

 No evidence whatever was found of the 

 presence of minute globular chloroplasts, 

 such as several investigators say are pres- 

 ent in certain fornis. In this investigation 

 the conclusion was reached that the cell 

 organization of these low plants can not 

 be successfully studied except in thin sec- 

 tions, cut longitudinally as well as cross- 

 wise. 



Chemical Stinndation of Algce: E. B. Liv- 

 ingston. 



The study was carried on with the poly- 

 morphic form of Stigeoclonium previously 

 worked with by the same author. In the 

 previous work it was shoAvn that with rela- 

 tively high osmotic pressure of the medium 

 the alga produces only spherical cells, a 

 Palmella or Pleurococcus form. With low 

 osmotic pressure it grows out with long 

 branching filaments. Zoospores are formed 



