September 13, 1894] 



NA TURE 



4/9 



results, show that the centrosomes retain their indi- 

 viduality tlirough every change. Couple with these facts 

 the discovery by Dr. Field of the entry of the centrosomes 

 into the spermatozoa of the echinodernis, and a quite 

 similarJstate of thin<j5 I have fmind to occur in mam- 

 mals, and there seems much evidence that the centro- 

 somes, unlike the other constituents of the sphere, retain 

 their individuality during successive mitoses, and are in- 

 corporated as an essential constituent of the spermatozoa. 

 Further, the well-known observations of Fol, and more 

 recently those of Fick, show clearly that these bodies 

 assume their old functions as dominants of the attractive 

 process in the initial steps of fertilisation. Their identity 

 through successive generations being thus maintained, the 



helms Institut, and while there came under the influence 

 of a profound teacher — Johannes Muller. He eventually 

 became a military surgeon, and continued in that position 

 till the end of ICS48, when he was appointed Assistant of 

 the Anatomical Aluseum of Berlin, and Teacher of 

 Anatomy at the Academy of Arts. 



In 1S47, that is, during his career as an army surgeon, 

 Helmholtz's essay, " Ueber die Hrhaltung der Kraft," 

 was published. In this, the principle of the conservation 

 of energy was developed. About Joule's researches on 

 the same subject, he knew at that time but little, and 

 nothing at all of those of Robert Mayer. He was led 

 to write the essay by an examination of Stahl's theory, 

 adopted by most physiologists, which accorded to every 



Fig. 4. 



■>R 



Fif.. I. Fig. 2. Fig. y 



important functions they perform in the division process 

 itself necessitates our regarding them, with \'an Beneden, 

 as organs of the cell, although, when viewed in such a 

 light, they will have to be disrobed of their more con- 

 spicuous radial and archoplasmic vestments. V.'ith 

 respect to these latter, in whatever degree they may be 

 present, it seems an unavoidable conclusion that they 

 can only be regarded as the effect produced by the in- 

 constant action of polarity or whatever power is exercised 

 by the centrosomes on the surrounding kytoplasm. 



j. E. S. MOOKE. 



HERMANN VON HELMHOLTZ. 



TTOXOURED and mourned by all, I'rof. von Helm- 

 ■'■■'■ holtz, one of the most brilliant men who have 

 devoted their lives to science, passed away at Charlotten- 

 burg, on -Sunday last. .Shortly before his death, the 

 Empress Frederick sent a telegram of inquiry as to his 

 condition, and upon hearing of his decease messages of 

 sympathy were sent to the sorrowing relatives by the 

 Emperor and herself This fact is a significant indica- 

 tion of the regard in which the representatives of science 

 are held in Germany. 



Hermann Ludwig Ferdinand Helmhollz was born 

 August 31, 1 82 1, at Potsdam, where his father, Ferdinand 

 Helmholtz, was Professor in the Gymnasium, his mother, 

 Caroline I'enn, being of an English family. While but a 

 schoolboy he developed a love for science, and studied 

 all the books on physics which his father's library con- 

 tained. They were very old-fashioned ; phlogiston still 

 held sway, and electricity had not grown beyond the 

 voltaic pile. When the class was reading Cicero or 

 Virgil, he was finding the paths of the rays in a telescope, 

 or developing optical theorems not usually met with in 

 text-books. .'\t that time there was little possibility of 

 making a living out of physics, so, acting on the advice of 

 his father, Helmholiz took up the sludv of medicine. He 

 entered the Army Medical School, the Friedrich Wil- 



NO. 1298, VOL. 50] 



• - a. 



living body the nature of a perpetuuin 

 mobile. The essay contained the results 

 ~! of a critical investigation of the question 

 j whether any relations existed between 

 j the various kinds of natural forces for 

 j perpetual motion to be possible. It was 

 I written for the benefit of physiologists, 

 I but, to Helmholtz's surprise, the physicists 

 I took up the doctrine of the conservation 

 j of energy, which some of these were in- 

 I clined to treat as a fantastic speculation, 

 I Jacobi, the mathematician, recognised 

 I the connection between the line of thought 

 I in the essay, and the principles investi- 

 I gated by Daniell, Bernouilli, d'Alembert, 

 and other mathematicians of last century, 

 and soon the members of the then young 

 Physical Society of Berlin accepted 

 Helmholtz's results. It is unnecessary 

 for us to dwell upon the marvellous in- 

 fluence that these results have had upon 

 physical science during the last half-century. The prin- 

 ciple of the conservation of energy has long passed 

 through the debatable stage, and some of the greatest 

 discoveries in thermodynamics and other branches of 

 modern physics have been deduced from it. 



In 1S49 Helmholtz went to Konigsberg as a Professor 

 of General Pathology and Physiology ; seven years later 

 he accepted a similar position at Bonn University. 

 While at the former University he designed the 

 ophthalmoscope for the diagnosis of diseases of the inner 

 parts of the eye — a discovery which shows the great 

 importance to the physiologist and physician of a 

 thorough knowledge of physical principles. The year 

 1S59 saw him occupying the chair of Anatomy and 

 Physiology at Heidelberg; and in 1S71 he was ap- 

 pointed Professor of Natural Philosophy in the Univer- 

 sity of Berlin, a post which he held until his death. 



The two great works of Helmholtz on " Physiological 

 Optics" and on the ".Sensations of Tone," are splendid 

 examples of the application of methods of analysis to the 

 two kinds of sensation which furnish the largest propor- 

 tion of the raw material for thought. In the first of these 

 works, the colour-sensation is investigated, and shown to 

 depend upon three variables or elementary sensations. 

 The study of the eye and vision is made to illustrate the 

 conditions of sensation and voluntary motion. In the 

 work on the " Sensation of Tone as a Physiological Basis 

 for the Theory of Music," the conditions under which 

 our senses are trained are illustrated in a yet clearer 

 manner. His researches threw a flood of light upon 

 what may be termed the mechanical, physical, physio- 

 logical, and psychological processes involved in seeing 

 and hearing. 



No good end would be served by enumerating Helm- 

 holtz's contributions to knowledge. The versatility of 

 his genius is well known among all workers in the realm 

 of nature. Mathematics, physics, physiology, and 

 psychology are but a few of the branches of knowledge 

 which have been enriched by his investigations. His 

 acquaintance with science was not only extensive but 



