534 



NA TURE 



[A 



I'KII. lO, 1902 



LETTERS TO THE EDITOR. 

 [ The Editor does not hold himself responsible for opinions ex- 

 pressed hy his lonespondenis. Neither can he undertake 

 to return^ or to cot respond with the writers of rejecel 

 manuscripts intended for this or any other part of NatUKE. 

 No notice is taken of anonvmous communications.'^ 



Transport of Molluscs by Waterfowl. 



Yesterday (March 19) I witnessed an interesting instance 

 of the capacity of quite small waterfowl to carry aquatic mol- 

 luscs of considerable size. A pheasant-tailed Jacana {Hydro- 

 phasianus c/iirtiri;us), which was at large, with partially 

 clipped wings, on the tank in the Museum grounds, had 

 attached to one of its feet a fresh-water mussel well over an inch 

 long, which remained there for about an hour and a half to my 

 knowledge. 



The Ja(,-ana, although quite a small bird, only about the size 

 of a turtle-dove, nevertheless flew quite as well with this burden 

 as without, covering as much as sixty yards at a flight, with its 

 legs naturally extended behind. 



Of course the partial clipping of its wings hindered it from 

 rising high and going oft' altogether ; but had it not been thus 

 handicapped I am sure it could have transported its burden for 

 miles if forced to leave the tank. 



I have had more than one specimen of this Ja9ana in 

 which a toe, or part of one, was missing, an accident which 

 might possibly be due to the pinch of a bivalve behaving as 

 described above. A fish or turtle might more probably be 

 guilty of such amputation, although the Jacana's slim green 

 toes look very like weed-stems when it is swimming, and the 

 resemblance might be protective so long as the bird floated 

 quietly without paddling. 



I find from my notes that six years ago I observed one of 

 some Tree-ducks (Dcndrocycna javanica) which I was then 

 keeping on this tank, with what appeared to be a big water- 

 snail remaining attached to its toe for some time. 



Indian Museum, Calcutta, March 20. Frank Finn. 



Preservatives in Milk. 



I HAVE been astonished to learn from your English Government 

 Blue-book about the scandalous, unnecessary and unnatural prac- 

 tice prevailing in England of putting drugs into milk for purposes 

 of its preservation — a wrong and unnecessary act of adulteration. 

 It is amazing that it should be pursued and for i>ne moment 

 permitted. Sour highly appreciated publication will, I am 

 certain, feel the necessity of defending nature's produce. All 

 milk drawn from healthy cows is yielded sterile. The remedy 

 against the use of drugs and late-refrigeration, ^c. ,isto purify and 

 preserve the milk in its natural sterile condition by quickly — on 

 drawing it — aerating, cooling and refrigerating it down to the non- 

 decomposing and non-fermenting temperature of 50^ Fahrenheit 

 or lower at the farms and rural factories before being sent off 

 from the country, and having it conveyed, so chilled, into 

 ordinary cold stores — the same as doubtless most of your butchers 

 have, and with less reason — at the town dairy premises. Meat 

 is so preserved and so conveyed, I understand, in England, and 

 it is not nearly so susceptible to decomposition. The totally 

 unnecessary consequences that are revealed' by your recent 

 official inquiry are scandalous. Dairy men evidently— and must 

 constantly— find the milk they have to sell, not only in 

 an advanced, but also dangerous state of fermentation, which, 

 in self-interest, thoy can only, however, temporarily sup- 

 press by the processes of drugging, late- refrigeration and 

 other disorganising practices, through neglect in the country of 

 purifying and cooling the milk at once when ilrawn warm from 

 the cow. There are plenty of simple portable appliances to 

 use for the purpose, so why should not English farmers have 

 them, and rural ice depots near railway stations for refrigeration 

 of milk, as well as Continental, and notably American, country 

 milk producers ? Your farmers and milk distributors certainly 

 need reform in their system, for you cannot possibly compete 

 in quality of milk, butter or cheese with other countries where 

 immediate purification by the practice of quick aeration and 

 refrigeration of milk is pursued down to a non-fermenting tem- 

 perature as soon as possible after being drawn from the cow. I 

 have heard of a new method of milk preservation based on the 

 infusion of gases (oxygen and carbonic acid) into milk. What- 

 ever may be the merits of this new process I am not prepared 



NO. 1693, VOL. 65") 



to say, but if drugs are to be prohibited, this infusion of pases 

 should be swept away with the rest of the doctoring methods- 

 of milk. By all means let the prohibition be utterly complete, 

 and thus allow the consumer to drink nature's production and 

 not chemical compounds. In this country (Belgium) the use of 

 any drugs has long been prohibited, and our milk is superior and 

 never complained about, and were drugs permitted a general 

 protest would result. L. J. Serin. 



Mont-sur-Marchienne, Charleroi, Belgium. 



[Mr. Serin does not seem to be aware of the fact that the 

 Departmental Committee on the use of Preservatives in Food 

 condemned the use of preservatives in milk. (See Nature, 

 December 5, 1901, p. 102.) — Editor.] 



Rearrangement cf Euclid Bk. I., pt. i. 



As very widespread attention is being paid to the question of 

 reform in geometrical teaching, and as a good many teachers 

 are convinced that in this country the reform must be in the 

 direction of a modification of Euclid's elements, I should be 

 glad to elicit opinions as to the following rearrangement of the 

 theorems in the first part of Book I. (to prop. 32, inclusive). 



First, the theorems relating to angles made by two inter- 

 secting straight lines, viz., I. 13, 14, 15. 



Then those relating to parallels, viz. 27, 28, 29, 30. Prop. 

 27 can be proved by superposition ; for, if a transversal EF 

 crossing two lines AB, CD makes the alternate angles equal, 

 the portion BEFD can be exactly superposed on CFEA, so 

 that, if AB, CD meet towards B, D, they must also meet 

 towards C, .\, which is impossible, . •. AB, CD are parallel. 

 I. 28 follows from I. 13 ; and 29, 30 from Playfair's axiom. 



By taking these propositions early, we are enabled to re- 

 arrange the propositions respecting triangles in such a way 

 that connected propositions are juxtaposed, which is of great 

 assistance to the memory and to the growth of orderly ideas in 

 the pupil's mind. The natural order would be to take those- 

 propositions which relate to a single triangle and then those 

 which deal with the comparison of two triangles. 



First, the fundamental theorem I. 32, with its corollaries, 

 including I. 16, 17, and Euclid's axiom (which is the converse 

 of 17). 



Then 5, 6 with their extensions, viz. 18, 19, to which might 

 be added the corollary that the perpendicular distance of a 

 point from a straight line is the shortest. 



Then 20, 21. 



Then follow the congruence theorems 26, 4, S, to which might 

 well be added the conditions for the congruence of right-angled 

 triangles in what would otherwise be the ambiguous case. 



And lastly 24, 25, which are extensions of 4, S in much the 

 same way as 18, 19 are extensions of 5, 6. 



If to these are added the simple locus theorems regarding the 

 locus of points equidistant from two given points, and the locus 

 of points equidistant from two intersecting straight lines, the 

 whole forms a well-rounded-ofV " First Part " of the deductive 

 course. 



The only innovation suggested here is the early introductior> 

 of the theorems relating to parallels. The effect of this is to 

 render the course much more compact and orderly than is 

 possible if the theory of parallels has to be approached through 

 I. 16. 



It is on the desirability (and the possibility, from the point of 

 view of examinations) of this innovation that I earnestly desire 

 opinions. 



There is one other modification tacitly adopted in the above 

 arrangement, and that is the cutting out of "constructions" 

 from the deductive course. I believe this requires no defence. 

 It is the first and greatest necessity, for any real improvement in 

 geometrical teaching, that the course of constructions should be 

 a parallel course to that of theorems, and not part of it. 



Coopers Hill, April 2. Ail red Loiji;e. 



Protoplasmic Networks. 

 In a presidential address delivered at Yale ( Con/rib., Botanical 

 Laboratory, Univ. Pennsylvania, ii., 1901. p. 183), Prof. 

 Macfarlane announces his discovery of a " linin and chromatin" 

 network continuous with the nuclear chromatin distributed 

 through the protoplasm of plant cells. Certain other observa- 

 tions lead Prof. Marfarlane to suggest that these run from cell 

 to cell, so that there is continuitv, not only of cytoplasm, but 

 also of the " hereditary substance." 



