264 



SCIENCE. 



LN. S. Vol. XVII. No. 424. 



virginica were put in a three per cent, 

 solution of cane sugar and then brought 

 under the influence of pure hydrogen. 

 Under such circumstances nuclei in the 

 resting stage can not divide, but nuclei 

 which have begun division can complete 

 it. No cell wall is formed ; when, however, 

 oxygen is again introduced, a cell wall is 

 formed. 



Experiment II., Influence of COj.— 

 Nuclear division can not take place in 

 nearly pure COj, nor can nuclei which 

 have begun to divide complete the division 

 as stated by Demoor. 



Experiment III., Influence of Ether. — 

 No resting nucleus can divide in ether. 

 In one per cent., three per cent., four per 

 cent., five per cent, and six per. cent, of 

 ether, nuclei that have begun to divide can 

 complete division and form a cell wall. 

 In seven per cent, ether nuclear division 

 - can not take place. Nuclei in ether do 

 not change from indirect to direct division 

 as stated by Nathanson. 



Experiment IV., Influence of Cold. — 

 At 2° C. nuclei can divide. At — 3° C. 

 or — 4° C. nuclei can not divide as stated 

 by Demoor. 



Experiment V., Influence of Chloro- 

 form. — In chloroform diluted one half 

 with water, nuclei that have begun to di- 

 vide can complete the division and a cell 

 wall is formed. 



Experiment VI., Influence of Ammo- 

 nium Carbonate. — In a one fourth per 

 cent, or one half per cent, solution of am- 

 monium carbonate, nuclei that have begun 

 to divide can complete division and a cell 

 wall is formed. A one per cent, solution 

 of ammonium carbonate kills the cell in 

 one minute and before nuclear division 

 can advance. 



New Examples of Diurnal Nutation: F. 

 L. Stevens, "West Raleigh, N. C. 

 Nutation similar to that exhibited by 



Helianthus is demonstrated by lantern 

 slides for several other genera, prominent 

 among them being Bidens, Amaranthus, 

 Ambrosia, Medicago, Melilotus, Artemisia, 

 Lespedesa, TrifoUum, etc. 



Problematic Fossils, supposed to be Sea- 

 iveeds, from the Hudson Group: David 

 White, Washington, D. C. 

 Slabs of calcareous shale, deposited in 

 shoal-water flats and marked with mud 

 cracks and iron stains, bear impressions of 

 fragments of supposed algse of singular 

 characters and distinctness. The fossils 

 represent a narrow sinuous axis, now flat- 

 tened, but probably nearly subcylindrical 

 originally, alternately and repeatedly fork- 

 ing at an extremely wide angle at inter- 

 vals of 1-2 cm., the subdivisions recurring 

 so as to describe nearly regular and equal 

 incomplete rings or semicircles about 3 

 em. in diameter. The lobes, which end ob- 

 tusely, nearly equal the axis in width, and 

 by their ring-like form and regularity in 

 alternate arrangement present a very strik- 

 ing appearance on the slab. The fossils 

 are true intaglio impressions, or trails, 

 destitute of carbonaceous matter. The 

 structure of the mould bears no evidence 

 of layers or wadding as in worm burrows. 

 They are tentatively regarded as fucoidal 

 and comparable to Palceophycus or Butho- 

 trephia, though it is possible that they rep- 

 resent extraordinary trails made by some 

 annelid or other animal organism. The 

 specimens were collected by Dr. Eobert 

 Hessler in Fayette County, Indiana. 



On Cxdtures of the Leaf-spot of the Grape, 

 Phyllosticta Labruscce Thm. : A. D. 

 Selbt, Wooster, Ohio. 

 The paper states the results of success- 

 ful efforts made at the Ohio Agricultural 

 Experiment Station, to secure the devel- 

 opment of the various stages in the growth 

 of this fungus on culture media. Peri- 

 thecia preceded by pycnidia were obtained 



