April 12, 1877] 



NATURE 



5^1 



retard the earth's rotation, but this is exactly balanced by the 

 counter-trades of the circumpolar vortexes, blowing from west 

 to east. 



I cannot agree with Mr. Clement Ley when he says that it 

 involves a fallacy to explain the mean winds, or great currents, 

 on one principle, and the actual winds, or temporary currents, 

 on another. If the great currents were much feebler in propor- 

 tion to the temporary currents than they are, the mean preva- 

 lence of east winds in the tropics, and of west winds in the 

 higher latitudes, would be discernible only as a residual fact 

 when a number of anemometric observations made at various 

 places were completely discussed. Joseph John Murphy 



The Germ Theory 



Your number for March 22 contains a review of my work on 

 the Germ Theory of Disease, which, in some points, conveys so 

 erroneous an impression of my exact position that I must ask 

 you to allow me space for a few remarks regarding it. 



Adverse criticism is what the author of such a book as mine 

 expects, and, to some extent, desires. 



A fair representation of his views and arguments, is what every 

 author may insist on as a right. 



It is the misleading manner in which my position is stated in 

 your review that has induced me to pen this note. 



To ov e or two of your statements I would refer in illustration 

 of what I complain. 



After referring to my expressed belief that contagia are living 

 organised particles — an opinion held by many eminent physicians 

 and men of science — your reviewer says : "If, however, the 

 particles in sheep-pox, small pox, and vaccine be the infectirg 

 matter, they are easily seen by the microscope, and ought, there- 

 fore, to be found in the blood, but such is not the case." This, 

 the old and stock argument against the germ theory, is specially 

 dealt with by me on two different occasions — at p. 25, et seq., 

 and at p. 204, et seq. If it was worth your reviewer's while to 

 raise this old objection to the germ theory, it was equally worth 

 his while to make some reference to my explanation of the face 

 on which it rests. This he has not done — a manifest unfairness. 



A little further on the review says : " Increased elimination of 

 urea is explained thus : The increased consumption of liquor san- 

 guinis by the conta^ium particles leads to increased formation of 

 retrogressive albumen and of urea. It seems by this that con- 

 tagium particles have livers and kidneys." 



Tlie part which I put in italics is put in your review within 

 inverted comma?, conveying thereby the impression that it is a 

 correct quotation from my book. It is far from being so. As 

 given by you, it is a misquoted short passage, separated from 

 its context, and altered to suit the purpose of your review. 



The chapter on increased elimination of urea is perfectly clear 

 and intelligible to any ordmary mind, and contains nothing 

 which justifies your reviewer in attributing to me, as he has done, 

 the absurd belief that contagia are possessed of livers and kidneys. 

 Neither is he justified in usmg the words " eat " and "drink " to 

 express the action of a minute organism on its environment. 

 Such phraseology can serve only to mislead those who are igno- 

 rant of the mode in which these organisms grow ; and is quit*? 

 inapplicable to any nutritive process which goes on in such 

 organisms as I have described contagia to be. 



Your reviewer quotes my statement that "if we were to bleed, 

 to purge, to give antimony to, or even simply to withhold food 

 and water from all the cases of typhus and enteric fever which 

 occur, there can be no doubt that we should find the mortality 

 from these diseases greatly increased ; " and remarks on this, 

 " Dr. Maclagan is right here, for by simplywithholding food and 

 water there can be no doubt that he would greatly increase the 

 mortality by starving his patients to death." Your reviewer 

 seems to be unaware that I refer in these remarks to a mode of 

 treating fever which at one time did prevail. 



To one other point I would refer in illustration of your re- 

 viewer's inaccuracy. 



He says " the heat of specific fevers is partly ascribed to the 

 propagation of the contagium causing increased consumption of 

 tissue. But increase of living matter causes the disappearance 

 of heat, not its production." 



Even according to this, your reviewer's own somewhat awkward 

 statement of the matter, the increa>cd heat is attributed by me 

 to increased consumption of tissue, indirectly brought about by 

 the propagation of the contagium. Nowhere do I say that in- 

 crease of living matter causes production of heat ; and nowhere 

 does your reviewer attribute such a statement to me. Quite the 



contrary. I distinctly say that the increased production of heat 

 results from increased disintegration of the tissues ; and your 

 reviewer distinctly attributes this saying to me. What, then, is 

 the meaning of the latter part of the sentence just quoted ? It 

 bears but one interpretation. V'^our reviewer attaches to the first 

 half of the quotation a meaning the reverse of that which it 

 conveys. While saying that I ascribe the increased heat to in- 

 creased consumption of tissue, he seems to think that he is saying 

 something quite different, and pens his criticism accordingly. If 

 he thus misunderstands his own statements, I need, perhaps, 

 scarcely be surprised at his sometimes misinterpreting mine, I 

 do object, however, to such misinterpretations and inaccuracies 

 appearing in so influential a journal as Nature. 

 Dundee T. Maclagan 



SEXUALITY IN PLANTS 1 

 'T^HE concluding part of the tenth volume of Prings- 

 -*• heim's yahrbiicher contains three papers, one of 

 them by Dr. Arnold Dodel, of Zurich, being of the 

 highest importance. This paper occupies the greater 

 part of the present Heft, and is illustrated by eight 

 coloured plates. The title is " Ulothrix zonula, its .Sexual 

 and Non-Sexual Reproduction, a Contribution to the 

 Knowledge of the Lower Limit of Sexuality in Plants." 

 The an atomy and life-history of the Ulothrix is exhaustively 

 treated, the whole paper being a model of careful and 

 accurate research, as well as a valuable contribution to 

 our knowledge of the lower plants. The paper is divided 

 into sections, of which the following is a short summary. 

 The results given are those obtained during fourteen 

 months' consecutive observation of the plant. The genus 

 Ulothrix has been divided into many species, but Dodel 

 shows that U. zonata is so variable in its different stages 

 that most of the so-called species must be reduced to 

 one. The alternation of generations is very remarkable 

 and divisible into four stages. During the progress of the 

 alternation of generation three distinct forms are to be 

 distinguished, two being filamentous generations, and the 

 third a zygospore generation. The filamentous gene- 

 rations are invariably produced non-sexually and repro- 

 duce themselves repeatedly, forming, in fact, the plant 

 known to systematic botanists as Ulothrix zonata. The 

 third generation, the zygospore, was unknown till dis- 

 covered by Dodel. In the long series of filamentous 

 generations two distinct forms are to be distinguished. 

 The first is produced non-sexually and is the autumn or 

 winter generation. It develops non-sexual macrozoo- 

 spores and quickly spreads the species in a given locality. 

 The second is a sexual stage developing microzoospores. 

 It arises from the non-sexual macrozoospore, and gives 

 rise to the microzoospores which by conjugation form the 

 third generation, the zygospore or zoozygospore. 



The production of the microzoospore-forming getiera- 

 tion terminates the series of filamentous generations. 

 This stage is found in spring and summer, and by giving 

 rise to the zygospores which by remaining in a state of 

 rest for some months during the hot dry summer weather, 

 reproduce the plant in the autumn. During the hot 

 weather the filamentous generations more or less com- 

 pletely disappear. The zygospore generation, although a 

 product of gamogenesis, is itself non-sexual. 



Ulothrix zonata exhibits polymorphism in a remark- 

 able degree, hence many forms looked upon as distinct 

 species must be suppressed. This opens up a wide ques- 

 tion in regard to other alga?, and shows how essential it 

 is to obtain an accurate knowledge of the life-history of 

 all forms. 



The cells of Ulothrix give rise to a variable number of 

 zoospores. A mother cell may form i, 2, 4, 8, 16, or 32 

 zoospores, theic being no obvious distinctions between the 

 sexual and non-sexual zoospores. On the one side ii the 

 large macrozoospore with four cilia, and then there is 

 every gradation down to the smallest microzoospore 



' Jahrbiicher fur wissenschaftliche Botanik. Herausgegeben von Dr. N. 

 Pringsheim. Zehnter Band, Viertes Heft. Leipzig : Engelmann, 1876. 



