,ro 



NA TURE 



[September 9, 1909 



FROF. EMIL CHRISTIAN HANSEN. 



IT is with profound regret that we have to announce 

 the death of Prof. Emil C. Hansen, director of 

 the Carlsberg Laboratory, Copenhagen, which 

 occurred after a brief illness on August 27. Born in 

 1842, he attended in his youtli the art school at Copen- 

 hagen, but subsequently, between 1871 and 1876, de- 

 voted himself to the study of science at Copenhagen 

 University. He entered the Carlsberg Institute in 

 1S77, where he commenced his memorable researches 

 on microbiology. 



Hansen's life-work was practically confined to the 

 study of the Saccharomycetes, but his researches in 

 this domain of biological .science stand out as a 

 model of thoroughness. Prior to his time little was 

 known concerning the different species of yeasts, 

 although so early as 1857 Bail had observed that 

 types of yeast existed giving rise to what he termed 

 " wild fermentations." This did not, however, at- 

 tract much notice among either scientific men or 

 technologists, and even Pasteur — who must ever be 

 regarded as the pioneer of biology as applied to the 

 fermentation industries — regarded bacteria alone as 

 the cause of diseases of beer. Rees, however, in 1870, 

 had arrived at the conclusion from his experiments 

 that brewery yeasts represent species which are quite 

 distinct from wine yeasts, and that still other species 

 are concerned in the secondary fermentation of beers 

 and in so-called "wild fermentations." None of 

 these observations were, however, convincing, and 

 the truth only became apparent after the publication 

 of the exact experimental data on the subject by 

 Hansen. 



In 1880, when Hansen first commenced his remark- 

 able studies on the Saccharomvcetes, biological 

 methods of isolating micro-organisms were but little 

 developed. The dilution method devised by Lister and 

 employed by that observer, as well as by Naegeli and 

 by Fitz, wa? the only one available, yet it was by 

 an improved modification of this extremely tedious, 

 not to say uncertain, method that Hansen succeeded 

 for the first time in cultivating yeasts from a single 

 cell. In his paper published in 1883 he described 

 accurately six species of Saccharomycetes. The sub- 

 sequent adoption by Hansen of the method of culture 

 on a solid substratum — which had been developed by 

 Koch — added much to the precision of his work, but 

 he always insisted that in order to obtain absolutely 

 pure cultures it was necessary in all cases to start 

 from a single cell. Some might, indeed, think that 

 he carried this injunction a little too far, in view of 

 the results which have been obtained in the isolation 

 of other micro-organisms by cultures from colonies; 

 but it must be remembered that Hansen's researches 

 were directed, not merely to the isolation of species, but 

 of varieties. 



Hansen's work consisted, however, not only in 

 isolating distinct species of the Saccharomycetes, but 

 he elaborated methods for their characterisation, and 

 for this purpose he made use of film-formation, and 

 more especially ascospore-formation, under definite 

 conditions of temperature. By the sporulation test 

 it is possible to detect i /900th to i /200th part of a 

 wild yeast — such as a S. Pastoriantis species — in ad- 

 mixture with S. cerevisiae. Thus the jnicrobiologist 

 was put in possession of a method for the quantitative 

 as well as the qualitative analysis of yeast mixtures. 

 Previously for the qualitative analysis of such mix- 

 tures morphological considerations alone were avail- 

 able, the results being rough and inconclusive, for 

 one and the same species may under different con- 

 ditions assume a different form. 



Practical brewers have long known that yeasts in 

 practice vary according to the system of fermentation 

 NO. 2080, VOL. 81] 



adopted ; it has even been suggested that a given type 

 of yeast consists of more than one variety or race, 

 and in this country, at all events, such a type is 

 always associated with a certain number of cells of 

 wild species. Whether these varieties, which seem to 

 be the result of environment, are immutable is a 

 moot point, and it may be pointed out that 

 Hansen at first believed that the top-fermentation 

 races of S. cerevisiae employed in this country were 

 under no conditions convertible into bottom-fermen- 

 tation races, but recently he found that the conversion 

 was possible. 



The employment of yeast grown from a single cell 

 has met with great success in Continental bottom- 

 fermentation breweries. Not so, however, in British 

 breweries. One of the first to give the system a trial 

 in this country was Dr. Horace T. Brown, who ultim- 

 ately abandoned it since he was not able to obtain a 

 satisfactory secondary fermentation ; and in confirm- 

 ation of Dr. Brown's results it has since been shown 

 and fully admitted by Hansen that for the secondary 

 fermentation of British beers, organisms other than 

 the normal S. cerevisiae are needful. In this connec- 

 tion it should be mentioned that Schionning re- 

 cently confirmed Clausen's observations that certain 

 torulse play an important role in bringing about the 

 secondary fermentation and conditioning of British 

 beers. 



Few men of science since Pasteur's time can lay 

 claim to a greater debt of gratitude from fermentation 

 technologists all over the world than Hansen. His 

 numerous papers are published in the Coin[itcs rendus 

 of the Carlsberg Laboratory, the Ceiitralblatt fiir 

 Bacteriologie und Parasitenktmde, the Annals of 

 Bataiiy, and the Journal of the Institute of Brewing. 



Arthur R. Ling. 



NOTES. 



Miss Dorothea Bate, already well known for her re- 

 searches in the caverns of Cyprus and elsewhere, has had 

 the good fortune to make a very remarkable and interest- 

 ing discovery in a cave in Majorca. On her return home 

 Miss Bate remarked that the cave contained only a few 

 bones of goats, but on further examination these despised 

 relics proved to indicate an entirely new type of an extra- 

 ordinary nature — in other words, neither more nor less 

 than a " rodent-goat." For the skull, which with certain 

 other remains is described by its discoverer in the September 

 number of the Geological Magazine, under the name of 

 Myotragus balearicus, is characterised by its extreme short- 

 ness, and the presence in the front of the lower jaw of a 

 single pair of incisor teeth, in place of the four pairs of 

 incisors plus canines characteristic of ruminants generally. 

 In all respects these incisors are rodent-like, growing from 

 persistent pulps, having the enamel restricted to the front 

 and outer surface, and presenting a terminal worn surface. 

 To explain this worn facet almost seems to require the 

 presence of a pair of upper incisors (the front of the skull 

 is unfortunately imperfect), and if such were really the 

 case a revision of the diagnosis of the Pecora would be 

 rendered necessary. The cannon-bones in both limbs are 

 remarkably short and wide, exceeding, apparently, in these 

 respects those of the takin and white goat. 



The article by Mr. E. B. Iwan-Miiller on " The Cult of 

 the Unfit," recently noticed in these columns, has called 

 forth a reply from Mr. Sidney Low in the Fortnightly 

 Review for September. It was not to be expected that Mr. 

 Iwan-Miiller's arraignment of ill-considered sentimentalism 

 in legislation should pass unchallenged, and Mr. Low's 

 rejoinder, entitled " Darwinism and Politics," argues 



