«30 



J^ATURE 



[DtctMiiEk 8, 1923 



fact need not lead to the conclusion that the function 

 of insulin is to convert the sugar reserves of the body 

 into pentose derivatives. L. B. Winter. 



W. Smith. 

 Biochemical Laboratory, 

 Cambridge. 



Fixation of Human Embryoloitlcal and 

 Cytolo^lcal Material. 



It is known that it is very difficult to obtain well- 

 preserved human material. Few medical men realise 

 that five or ten minutes after the tissue has been 

 removed, or after death, plasmolytic changes super- 

 vene, and in the fixed and stained sections the 

 chromosomes have clumped badly, and the delicate 

 Upoid cytoplasmic organellai have become abnormal, 

 or completely macerated. Recently, I have been 

 studying certain human material, and find that 

 nearly every type of histological preparation can be 

 made from two fixing fluids as follows : one of the 

 surgeon's assistants is given two bottles, one of Da 

 Fano's cobalt nitrate formalin fluid, and one of 

 Regaud's formalin-bichromate fluid. Pieces of tissue 

 as large as the thumb may be thrown into these 

 bottles, and afterwards cut into smaller pieces when 

 they have been brought to the laboratory. It is 

 better to change into new fluid at once, especially 

 if the organ is very vascular, and the fixing fluid 

 mixed with blood. 



For human material I find that fixation overnight 

 in the Da Fano fluid gives the best results. Next 

 morning some of the pieces are taken through as 

 usual for Da Fano's method (" Microtomists' Vade- 

 mecum," p. 437), but other pieces are washed in 

 distilled water for ten or fifteen minutes and trans- 

 ferred some to 2 per cent. OSO4, others to Champy's 

 fluid (chromeosmium). The OSO4 pieces are used 

 for the Sjovall method {ibid. p. 331). From this 

 batch of material, originally fixed in Da Fano, one 

 gets sections which generally show the inner Golgi 

 apparatus (Da Fano and Sjovall), the mitochondria 

 (chromeosmium and sometimes Sjovall), neutral fat 

 and lipoids (chromeosmium), and general nuclear 

 structures and mitochondria (Da Fano fixation, stain- 

 ing in iron haematoxylin) . 



The other batch of material, fixed in Regaud's 

 formol-bichromate, is partly carried through for the 

 Regaud-Bensley-Cowdry method {ibid. p. 324), but 

 other pieces of tissue are taken through Schridde 

 {ibid. p. 325). These methods give the mitochondria 

 (Regaud), mitochondria and fat (Schridde), and such 

 sections stain nicely in safranin — light green, and 

 in Mann's methyl blue eosin. For secretion and 

 excretion granules, zymogen, yolk, fat, Golgi ap- 

 paratus, and mitochondria, these two batches of 

 material will give complete results. 



For chromosomes, a batch of material in some 

 Bouin formula {ibid. p. 306) is recommended. 



J. Bronte Gatenby. 



Zoological Department, Dublin University, 

 November 7. 



Linnean Nomenclature. 



In the admirable review of Dr. Daydon Jackson's 

 " Linnajus " (Nature, November 17) there is one 

 paragraph (last on p. 715) from which I am not sure 

 that I extract all the meaning. This may be because 

 I am a systematic zoologist and not a botanist ; but 

 I did begin my work on those lines with the study of 

 Linn^'s " Philosophia botanica." That book taught 

 me that the notnen triviale was no entity, merely a 

 part of the nomen specificum, which consists of the 



NO. 2823, vol. 112] 



nomen genericum qualified by the nomen trivia: 

 Thus, " man " being the genus, " a good man " is ti 

 species : but " good " cannot stand apart from 



man," for it is relative to " man " alone. Now 

 take your ffood man and make him an admim* ' 

 may be a Dad admiral. Is that what the r< 

 means ? Does he imply that, if a species be 

 transferred to another genus, the nomen trt 

 open to change ? If this be his meaning, u.~.. .. 

 seems to ignore the distinction between a mere name 

 and an epithet. When Jane Smith marries John 

 Brown, she becomes (by custom) Jane Brown. She 

 may thereby even change her nationality, but she 

 remains Jane, and that is how we identif 

 although ' Jane " by itself is meaningless. 



What then, some of us are asking, are the " piulo- 

 sophical jxjsitions " from which we have retreated ; 

 what are the " sound scientific principles" we liavc 

 abandoned ? F. A. Bather. 



I REGRET to learn that one of my remarks ha- 

 proved obscure to zoologists. A note by Linnaeus 

 that nomen specificum sine generico est quasi pistillum 

 sine campana is accompanied by a cross reference to 

 the denominational canon nomen specificum sine 

 generico est quasi campana sine pistillo. The generalisa- 

 tion of the exemplar lends emphasis to the axiom 

 embedded in the canon. That axiom was almost 

 universally accepted by botanists in Great Britain 

 until 1905, when representatives of their science, in 

 international congress assembled, decided by a 

 majority vote that the two portions of a nomen 

 specificum may receive differential treatment. I am 

 satisfied that, in reaching this conclusion, the botanists 

 who constituted the majority when that vote was 

 taken abandoned sound scientific principles and 

 retreated from a philosophical position secured by 

 Linnaeus for botany. It may be that zoologists 

 regard as justifiable the botanical practice which 

 ignores the axiom accepted here until 1905 ; if so, 

 there is no more to be said. But, that further mis- 

 understanding be avoided, I may explain that 1 

 accept the principle of government by majority ; 

 whatever be the merit in civic life of conscientious 

 objection and passive resistance, I regard both as 

 unsuitable methods in descriptive science. This does 

 not deprive me of the right, when dealing with the 

 teaching of Linnaeus, to express my conviction that 

 the practical application of a particular Linnean 

 canon which prevailed before 1905 was sound, and 

 that the alternative practice, which obtains in botany 

 to-day, is less satisfactory. I may add that I have 

 not had in mind any of the methods in use in the 

 denomination of individuals, but the teaching of an 

 English naturalist, contemporary \vith Linnaeus, in 

 respect of analogous reasoning. 



The Reviewer. 



Bessemer Steel. 



In a review in the issue of Nature of November 17, 

 p. 716, of the second volume of Roscoe and Schor- 

 lemmer's " Treatise on Chemistr\'," the following 

 sentences occur : — " The revisers have been j)erhap>s 

 a little too careful in retaining old matter in the text. 

 The full details which are still given of the Leblanc 

 soda process and of the Bessemer process for steel 

 are really of historical interest only now that the 

 last Leblanc plant and Bessemer converter have been 

 shut down." 



I have consulted the Statistical Bulletin of the 

 National Federation of Iron and Steel Manufacturers, 

 which gives the official figures of steel production in 

 Great Britain at the present time, and I find that in 



