788 



SCIENCE. 



[N. S. Vol. XI. No. 281. 



that the low depressed areas and local basins 

 are caused bj' the leaching out of the soluble 

 materials from the underlying beds. ' The 

 Origin of Nitrates in Cavern Earths,' by Wil- 

 liam H. Hess. The author finds from a study 

 of cavern earths and from many analyses that 

 the nitrates are derived from the soil layers 

 above the caverns and are carried into the cav- 

 erns by the percolating waters and are finally 

 left in the cavern earths by the evaporation of 

 the vi^ater. ' The Calcareous Concretions of 

 Kettle Point, Lambton County, Ontario,' by 

 Reginald A. Daly. The article is illustrated 

 with six reproductions of photographs of these 

 noted concretions and after a somewhat ex- 

 tended discussion of the subject of concretion- 

 ary growths, the author concludes that these 

 particular concretions ' ' were formed in place 

 in the shales and antedate the period of joint 

 development and final consolidation of the sur- 

 rounding rock, that the local deformation of 

 the shale accompanied the crystallization, that 

 the energy of the deformation was derived 

 from the change of volume induced by the 

 breaking up of the bicarbonate into the mono- 

 carbonate and the fluid biproducts." ' Ants as 

 Geological Agents in the Tropics,' by John C. 

 Branner. The author concludes that the geo- 

 logical work of ants in the tropics is much 

 more important than that of the earthworms 

 in the temperate regions and he records a num- 

 ber of observations on the point. ' Variations 

 of Glaciers,' by Harry Fielding Reid. A sum- 

 mary of the fourth annual report of the Inter- 

 national Committee on Glaciers is given. Under 

 the section of Studies for Students, Dr. E. R. 

 Buckley gives a very comprehensive discussion 

 of ' The Properties of Building Stones and 

 Methods of determining their Value.' The 

 author treats especially the economic phase of 

 the subject. 



W. G. T. 



SOCIETIES AND ACADEMIES. 



ZOOLOGICAL CLUB, UNIVERSITY OF CHICAGO. 



MEETINGS OF FEBRUARY AND MARCH, 1900. 



At the meeting of February 14th, Mr. W. J. 

 Moenkhaus presented a paper entitled ' Some 

 Stages in Hybrid Development ' giving some of 

 the results of his experiments upon the produc- 



tion of hybrids among fishes, and Miss Mary 

 Hefferau reviewed Rand's papers on regenera- 

 tion and regulation in Hydra. The following 

 is an abstract of Mr. Moenkhaus' paper : 



Of some twenty crosses made between some 

 of our commoner marine and fresh water fishes 

 there was not a single failure of impregnation, 

 though many of the crosses were between very 

 distantly related forms — soft-rayed and spiny- 

 rayed species. The per cent, of eggs impreg- 

 nated was, as a rule, quite large, but this bore 

 no relation to the nearness of relationship. 

 Two combinations gave beautiful instances of 

 what a study of the nuclear conditions has 

 shown to be dispermy, fifty per cent, of the 

 impregnated eggs falling directly into four cells, 

 the remainder into two. In all crosses segmen- 

 tation was carried through. Four crosses went 

 to completion of gastrulation, forming the neural 

 tube, but no optic vesicles. The remainder 

 hatched. From crosses among the trout it ap- 

 peared that the formation of the tail is a diffi- 

 cult process. Considering in this connection 

 the common phenomenon of infertility, it seemed 

 that in hybrid fishes there were at least four 

 pretty definite stages in development that are 

 critical : (1) beginning and (2) close of gastrula- 

 tion ; (3) formation of tail bud, (4) formation of 

 the sexual elements. 



The nuclear behavior during fertilization and 

 during degeneration in these partially success- 

 ful crosses is being studied. 



The session of February 28th was devoted to 

 two papers ; a review and critique by Mr. E. 

 R. Downing of Delage's recent work ou the 

 fertilization and development of enucleated 

 egg-fragments, and a review by Miss Anne 

 Moore of Calkin's paper on ' Mitosis in Nocti- 

 luca.' A few of the more important points 

 touched upon by Mr. Downing were as follows : 



Delage finds in embr3'os produced by the 

 fertilization of enucleated egg-fragments the 

 normal number of chromosomes. He claims to 

 demonstrate (1) a maturation of the cytoplasm 

 corresponding to, but independent of, that of 

 the nucleus ; (2) that enucleated eggs resist 

 hybridization as well as entire eggs and that, 

 therefore, the nucleus has nothing to do with 

 such resistance ; (3) that the female nucleus is 

 inert and the male excitable. The latter con- 



