546 



NA TURE 



[October 7, 1897 



metallic dome is not in any way connected metallically 

 with the ground. The rareness of thunderstorms is 

 accounted for by the presence of the central crater, the 

 smoke and hot vapour of which act as a lightning 

 conductor on a large scale. 



The climate in the neighbourhood of the mountain is of 

 a very varied nature. Except in the summer months the 

 summit is always covered with snow, and it is therefore 

 very cold. At the base, on the other hand, the weather 

 is warm, and the vegetation varies from tropical to arctic 

 species. On ascending the mountain one meets with 

 cacti, oranges, olives, vines, corn, ferns, astragal, chest- 

 nut trees and pine trees, up to a height of about 2000 

 metres. At a higher altitude only rock, volcanic sand, 

 -and snow are found. 



After an outbreak of the volcano it is natural to sup- 

 pose that the snow is generally melted by the hot lava. 

 It is of interest, however, to note that a layer of volcanic 

 •cinders has been known to protect the snow from lava at 

 a temperature of about 1000% so that when covered by it 

 the snow was but slightly melted, and the lava formed a 

 black covering in contrast to this white background. 



The view from the summit of Mount Etna is described 

 as most magnificent, extending nearly 200 kilometres in 

 all directions. This is due to the fact that the air at 

 this height is reduced to a third of its density, and is of 

 extreme transparency. 



FRITZ MULLER. 

 'T^HE death of Dr. Fritz Miiller, which took place on 

 -*■ May 21 at Blumenau, in South Brazil, has inflicted 

 upon science a loss, the importance of which needs no 

 pointing out. Although the greater part of his life was 

 passed at a distance from the centres of scientific 

 thought, and his natural modesty and self-effacement left 

 him indifferent to his own fame, it has long been recog- 

 nised that the qualities of observation and interpretation 

 which drew from Darwin the title of " the prince of 

 observers," have earned him a position as one ■ of the 

 greatest and most original naturalists of the century. 



Johann Friedrich Theodor Muller was born on March 

 31, 1822, at Windisch-Holzhausen, in Thuringia, where 

 his father was pastor. After receiving his schooling at 

 Erfurt, he began the study of pharmacy, but shortly 

 afterwards went to Berlin as a pupil of his distinguished i 

 namesake, Johannes Muller, the zoologist. As soon as 

 he had taken his doctor's degree, for which he wrote a 

 thesis on the leeches of the neighbourhood of Berlin, he 

 settled at Erfurt as a teacher of science. The occupa- 

 tion, however, proved uncongenial, and he again changed 

 his studies, and turned to medicine, with a view to be- 

 coming a ship's surgeon, and thus gaining opportunities i 

 for travel and for zoological work in foreign countries. | 

 During this early period he began gradually to make a 

 name for himself in science by the occasional publica- 

 tion of various morphological and descriptive papers on 

 leeches and Crustacea. 



In 1852 the liberal character of his political views 

 brought about a crisis which led to his leaving Germany j 

 and betaking himself to Blumenau, on the river Itajahy, 

 just outside the limits of the tropics, where, his educa- 

 tion and tastes notwithstanding, he settled down to the 

 occupation of a farmer. Henceforward Brazil was his ' 

 home, and to this fact and the freedom it brought from 

 the limits set to observation by travel and temporary I 

 residence is largely due his distinctive position among ' 

 naturalists. Under less favourable conditions much of i 

 his work, particularly on morphological subjects and on \ 

 matters involving experiment such as the hybridisation 

 of plants, must have been impracticable. Nevertheless, | 

 his expatriation put an end to research for some years, I 

 until an appointment as teacher of mathematics at the | 



NO, 1458, VOL 56] 



gymnasium of Desterro, on the island of Sta. Catharina, 

 gave him the wished-for opportunity, and he began 

 assiduously to study the invertebrates of the Brazilian 

 coast, and to overcome the difficulties which the absence 

 of a properly-equipped zoological station and his re- 

 moteness from literature and fellow-workers entailed. 



From 1857 onwards he published a rapid succession 

 of papers, chiefly in Wie_s,tnann^ s Archtv, on ccelente- 

 rates, annelids, and especially Crustacea, with the trans- 

 formations of which he was much occupied. Develop- 

 ment, in fact, had at all times a great attraction for him, 

 and he was the first to observe and describe the larval 

 stages of a brachiopod and o^ Sqiiilla. The material for 

 several memoirs was furnished by parasitic forms. He 

 described an anemone, Philomedusa^ parasitic on a 

 medusa, and made careful studies of such degraded 

 Crustacea as Entoniscus and Sacculitia, for the latter of 

 which, together with its allies, he formed the family 

 Rhizocephalidae. During this period his work was al- 

 most entirely concerned with morphological subjects, 

 and it was not until the " Origin of Species " had brought 

 a new interest and significance to the relations between 

 structure and bionomics that he devoted close attention 

 to field observation. 



He must have become acquainted with the " Origin" 

 very soon after its publication, and probably received a 

 copy of it from his younger brother and devoted cor- 

 respondent, Hermann Muller of Lippstadt. His initial 

 attitude towards the book appears to have been critical 

 rather than receptive, for he admits that it was an ob- 

 servation of his own which gave him the first decided 

 impulse in its favour. But he was not long in finding 

 that he could unreservedly accept its principles and 

 devote his energies to their support ; and the theory of 

 natural selection gave a definite direction to the whole of 

 his subsequent work. 



The observation which determined his adherence to 

 the theory of evolution was the discovery of the nauplius- 

 larva of Penceus^ a genus of prawns. Important as it is 

 from its bearing on the phylogeny of the Crustacea, in 

 which malacostracous nauplius was previously unknown, 

 and its influence on Miiller himself, it has not even yet been 

 fully confirmed. Miiller succeeded in breeding the 

 protozoaja-stage from his nauplius, but had to build up the 

 further steps in the development from a series of captured 

 examples. Here was room for. error, and his account 

 consequently met with a criticism which induced him, in 

 spite of an expressed dislike to going twice over the 

 same ground, to return to the defence of his observations 

 in 1878. Four years later Prof W. K. Brooks succeeded 

 in rearing PeiicEus from a protozo;i?a, " identical with that 

 developed by Fritz Miiller," but the assumption involved 

 in this statement was such as to prevent the matter from 

 being regarded as settled, and Miiller's account, though 

 presumptively correct, is still accepted with reserve by 

 some carcinologists. 



The philosophic bent of his mind soon led Muller to 

 recognise the possibility of testing the principles of 

 evolution by applying them towards the building-up of 

 the phylogeny of some group of animals, and ascertaining 

 how far the theoretical results obtained were reconcilable 

 with the observed facts of development. The idea was 

 put into practice for the Crustacea in a little book pub- 

 lished in 1865, the well-known " Fiir Darwin," which had 

 a great success in spite of its technical character and 

 limited scope. This success was probably due not 

 merely to the value of its accounts of crustacean de- 

 velopment, which embody the main results of Miiller's 

 own researches, and the then novel support which the 

 deductive argument brought to evolution, but also to the 

 brilliant simplicity of a title which disclosed nothing 

 beyond the fact of his advocacy and would have served 

 even better to cover the whole of his subsequent writings. 

 At that time the principle of evolution itself was at stake, 



