NATURE 



[Nov. 7, 1889 



tions. The able attempt of Van der Waals to bring both 

 yapour and liquid within the grasp of a single theory is 

 complementary to the extension by Crookes, Hittorf, and 

 Osborne Reynolds of our knowledge of phenomena which 

 are best studied in gases of great tenuity. 



The gradual expansion of thermodynamics, and in 

 general of the domain of dynamics from molar to mole- 

 cular phenomena, has been carried on by Willard Gibbs, 

 J. J. Thomson, and others, until, in many cases, theory 

 seems to have outrun not only our present experimental 

 powers, but almost any conceivable extension which they 

 may hereafter undergo. 



The pregnant suggestion of Maxwell that light is 

 an electro-magnetic phenomenon has borne good fruit. 

 Gradually the theory is taking form and shape, and the 

 epoch-making experiments of Hertz, together with the 

 recent work of Lodge, J. J. Thomson, and Glazebrook, 

 furnish a complete proof of its fundamental hypotheses. 

 The great development of the technical applications of 

 electricity has stimulated the public interest in this science, 

 and has necessitated a more detailed study of magnetism 

 and of the laws of periodic currents. The telephone and the 

 microphone have echpsed the wonders of the telegraph, and 

 furnish new means of wresting fresh secrets from Nature. 

 Science has become more than ever cosmopolitan, 

 owing chiefly to the imperative necessity for an early 

 agreement as to the values of various units for a com- 

 mon nomenclature, and for simultaneous observations in 

 widely separated localities. International Conferences 

 are the order of the day, and the new units which they 

 have defined are based upon experiments by many first- 

 rate observers in many lands, amongst whom the name o 

 Lord Rayleigh stands second to none. 



On the side of chemistry the periodic law of Mendeleeff 

 has become established as a generalization of the first 

 importance, and the extraordinary feat of foretelling the 

 physical properties of an as yet undiscovered element has 

 attracted to it the attention of the whole scientific world. 

 The once permanent gases are permanent no more. 

 Dulong and Petit's law has found a complement in the 

 methods of Raoult. The old doctrine of valency is giving 

 way to more elastic hypotheses. The extraordinary pro- 

 gress of organic chemistry, which originated in the work 

 and influence of Liebig and the Giessen school, has con- 

 tinued at an accelerated rate. The practical value of even 

 the most recondite investigations of pure science has again 

 been exemplified by the enormous development of the 

 coal-tar industry, and by the numerous syntheses of 

 organic products which have added to the material re- 

 sources of the community. 



The increase of our knowledge of the sun by means of 

 localized spectroscopic observation : the application of 

 photography to astronomy, and more recently still the 

 extension and generalization of the nebular hypothesis 

 are perhaps the most remarkable developments of those 



branches of science which relate to astronomy. Stars 

 which no human eye will ever see are now known to'us as 

 surely as those which are clearly visible. The efforts 

 to reduce nebulfe, comets, and stars under one common 

 law, as various cases of the collision or aggregation 

 of meteoritic swarms, and the striking investigations of 

 Prof. Darwin on the effects of tidal action, and on the 

 application of the laws of gases to a meteoritic plenum, 

 give promise of a fuller knowledge of the birth and 

 death of worlds. 



In the biological sciences, the progress during the last 

 twenty years has consisted chiefly in the firm establish- 

 ment of the Darwinian doctrine, and the application of 

 it and its subordinate conceptions in a variety of fields of 

 investigation. The progress of experimental physiology 

 has been marked by increasing exactitude in the appli- 

 cation of physical methods to the study of the properties 

 of living bodies, but it has not as yet benefited, as 

 have other branches of biology, from the fecundating 

 influence of Darwin's writings : hence there is no very 

 prominent physiological discovery to be recorded. The 

 generation of scientific men which is now coming to 

 middle age has been brought up in familiarity with Mr. 

 Darwin's teaching, and is not affected by anything like 

 hostility or a priori antagonism to such views. The 

 result is seen in the vast number of embryological re- 

 searches (stimulated by the theory that the development 

 of the individual is an epitome of the development of the 

 race) which these twenty years have produced, and in the 

 daily increasing attention to that study of the organism as 

 a living thing definitely related to its conditions which 

 )arwin himself set on foot. The marine laboratories 

 of Naples, Newport, Beaufort, and Plymouth, have come 

 into existence (as in earlier years their forerunners on 

 the coast of France), and served to organize and facili- 

 tate the study of living plants and animals. The 

 Challenger and other deep-sea exploring expeditions 

 have sailed forth and returned with their booty, which 

 has been described with a detail and precision unknown 

 in former times. The precise methods of microscopic 

 study by means of section-cutting — due originally to 

 Strieker, of Vienna — have within these twenty years made 

 the study of cell-structure and cell-activity as essential a 

 part of morphology as it had already become of physio- 

 logy. These, and the frank adoption of the theory of 

 descent, have swept away old ideas of classification and 

 affinities, and have relegated the Ascidian ",'polyps " of 

 old days to the group of Vertebrata, and the Sponges to 

 the Coelenterates. The nucleus of the protoplasmic cell 

 — which twenty years ago had fallen from the high 

 position of importance accorded to it by Schwann — 

 has, through the researches of Biitschli, Flemming, and 

 Van Beneden, been reinstated, and is now shown to be 

 the seat of all-important activities in connection with cell- 

 division and the fertilization of the Q'gg. The discovery of 



