July 5, 1894] 



NA TURE 



237 



pally to the amounts of heat evolved by explosion in a closed being aggregated about the dividing nuclei in spherical iiia>ses. 



vessel, and the quantity ani composition of the gases produced. Resulting apparently from this division, flagellated swarm cells. 



The following lal)le contains the results of some of the experi- having a diameter of 3-4/1, are produced, which escape, leaving 



meats : — an empty shell. 



Table Indicating the Quantity of Heat, also the Volume and Analysis oj 'he Gas developed per gr.i in with Nitro-gljueriii, 

 Nittocellulose, and with several different Combinations of these two Explosives made at Ardeer Factory. 



Compoiition of explosive. 



Calories 



per 



gram. 



Total volume 

 Permanent Aqueous ofeas 



gas, vapuur. calculated at 



o and 76 > mm. 



Per cent, composition of permanent Coefli- 



gases. cientof 



_ poten- 



I tial 



O^ CO CH, ' O H N energy. 



I A. Nitroglycerin 1652 



1 B. Nitro - cellulose (nitrogen = ij 3° 



I per cent.) 106 1 



I 



j ( 50 per cent, nitro-cellulose (N = 1 



C. ' 12-24 per cent.) / 1349 

 ( 50 per cent, nitro-glycerin 1 



\ 50 per cent, nitro-cellulose (N = I 



D. 133 per cent.) > 14IO 

 ( 50 per cent, nitro-glycerin ) 1 



( 80 per cent, nitro-cellulose (N = 1 

 K. ■ 12-24 per cent.) \ ' 1062 



[ 20 per cent, nitro-glycerin ) 



1 80 per cent, nitro-cellulose (N = 1 

 F. 13 30 per cent. 1 / 1 159 



' 20 per cent, nitro-glycerin ) 



I 35 P^f cent, nitrocellulose (N = i 

 (, I 13-30 per cent.) I j^So 



I 5 per cent, vaseline j 



1,60 ,, ,, nitro-glycerin j \ 



— — 4-0 



'"■I 957 



120 20-T lOOI 



627 



256 



863 



26-7 398 0-5 — 128 20-2 1105 



Results are also given when several recognised smokeless 

 powders were fired under various conditions. 



The authors are continuing their investigations, and are 

 especially endeavouring to measure the actual temperature of 

 explosion, in which direction considerable success has been 

 latlained. 



June 7. — "Contributions to the Life-History of the Fora- 

 minifera." By J. J. Lister, St. John's College, Cambridge. 



In this paper it is shown from an examination of a large number 

 ijf specimens of Polystomella crispa {Linn), that the in lividuals 

 •f this species fall into two sets, corresponding with the forms 

 A and B (of Munier-Chalmas and Schlumberger), which have 

 been shown to exist in species oi Niimmii/itida, Miliolitiic, and 

 'Other families of Foraminifera. The two forms may be distin- 

 Iguished as megalosplieric and microsphctic, being characterised 

 by a marked difference in the size of the chamber occupying the 

 centre of the shell. 



Associated with this difference in structure there is a marked 

 (difference in the nuclei of the two forms. 



j Individuals of the microspheric form, whose central chamber 

 is about 10 ju in diameter, have many small nuclei distributed 

 through the inner chambers. Evidence is brought forward to 

 jshow ihat in ihis form the nuclei multii)Iy at hrst by simple 

 division, and that ultimately they give off portions of their 

 substance, which become distritiuted through the proto- 

 iplasir. in the form of irregular deeply staining strands. The 

 jultimale fate of the microspheric form was not traced in 

 .Polystomella. 



] The megalospheric form, whose central chamber is gener- 

 'lly ahout 70/4 in diameter, has, in the usual condition, a 

 .ingle large nucleus which grows in si^e with the grow-th of the 

 Protoplasm, and p.asses from chamber to chamber, moving to- 

 «ards the centre of the protoplasm contained in the series of 

 ;hambers. There is evidence to show that in this firm, also, the 

 lucleus parts with portions of its substance. Ultimately the 

 lucleus disappears, and in its place hosts of minute nuclei ( 1-2 /i 

 n diameter) are found, which eventually become evenly dis- 

 ributed and divide by karyokinesis, the entire protoplasm 



NO. 1288, VOL. 50] 



In Orhitolites complanala (Lamck.), in which species the mi- 

 crospheric form attains the larger size, specimens of this form, 

 with young in their peripheral annuli (brood chambers) were 

 examined. It was found that the protoplasm was withdrawn 

 from the central chamber?, being represented by the megalo- 

 spheric young massed in the brood chambers. The young con- 

 tain a nucleus in their primordial chamber, which maintains this 

 position during a large part of the period of growth of this form. 

 While the production of megalospheric young by a micro- 

 spheric parent, which was recorded by Brady, was thus con- 

 firmed, the production of megalospheric young by a megalo- 

 spheric parent was also observed in three cases. 



The relation of nuclear characters to the two forms was 

 analogous to that found in Polystomella, and a similar relation 

 was found in Rotalia beccarii {Linn.) and Calcarina hispida, 

 Brady. 



In conclusion, the question of the relationship of the two 

 forms, under which the Foraminifera present themselves, is dis- 

 cussed, and reasons are urged for regarding ihem as distinct 

 from their origin. 



The hypothesis that they represent the two sexes is negatived 

 by the case of Orbitolita in which both forms have been found 

 producing the young of the megalospheric form, a condition 

 mcompatilde with the view that either is male. 



It is suggested that the two forms are members of a recurring 

 cycle of generations, and on this view it must he supposed, from 

 the condition presented by Orhitolites, that the megalos|iheric 

 form may, at least in this genus, be repeated for one or more 

 generations before the microspheric form recurs. 



June 7. — "Niagara Falls as a Chronometer of Geological 

 Time." By Prof J. W. Spencer. 



Various estimates of the age of Niagara Falls already have 

 been published, the maximum being 55,000 years, the minimum 

 6000. The author, after describing the topography and geo- 

 logy of the district, calls attention to the fact that the Niagara 

 river in pteglacial times had no existence. The peculiar exten- 

 sion of the chasm at the Whirlpool and the buried valley at St. 

 David's belong to a separate and shallower buried valley. 



