322 



KNOWLEDGE. 



September, 1913. 



beech tree showing a patch of phosphorescence 

 eight inches square. It was therefore surmised 

 that the birds had inhabited holes infested by 

 this bacterium. The other theory was that dampness 

 and uncleanliness of the covering of the breast had 

 favoured a sudden growth of luminous fungi peculiar 

 to feathers. This explanation appears to have been 

 more plausible ; for in the contact theory it would 

 seem that the wings and head, rather than the 

 breast, would be likely to touch the sides of the 

 hole. Yet these parts produced little or no light. 

 Again, it would necessitate the bird being a tree-hole 

 dweller, whereas similar cases have been observed 

 on Canadian blue herons, for which this kind of 

 life is impossible. 



The phenomenon is not confined strictly to wild 

 birds. Cases are also found among domestic pigeons. 

 The locating of the light on the breast can be ex- 

 plained by the fact that the feathers are finer and 

 thicker on that part of the body than on any other, 

 except the neck. It is also a part that the bird can- 

 not thoroughly clean, and will therefore retain the 

 greater part of the germs and dust gathered in flight. 

 The peculiar increase of light during flight is prob- 

 ably due to a chemical action of the air producing 

 superoxygenation, as it is well known that the agita- 

 tion of a medium containing phosphorescent particles 

 intensifies the luminosity of the latter. 



The balance of argument is thus in favour of the 

 fungi theory, and the latest observations of Senor 

 Elorza in Spain are a confirmation of it. On 

 several nights he saw a couple of luminous birds. 

 Upon inquiry he was informed that they had been 

 noticed for several years, that they lived in cliffs 

 near by, and that they disappeared in the month of 

 May. The description given by him did not answer 

 to that of the Barn Owl, and it is to be supposed 

 that we are in presence of another bird, one of 

 nocturnal habits, offering a similar case of phos- 

 phorescence. These specimens did not live in trees, 

 but in cliff-holes. Their disappearance in May is 

 accounted for, as in the other cases, by the spring 

 moulting of the feathers. 



It might be of interest to look back to the works 

 of the earlier naturalists and note that several 



observers were aware of the existence of luminous 

 birds. The first to record their appearance was 

 Pliny. He mentions them in his account of the 

 Hercynian forest (" Historia Mundi," X, 47). Two 

 hundred years later Solin, in the twentieth chapter 

 of his " Polyhistoria," alludes in much the same 

 way to what the great Latin naturalist had observed : 

 " Soltus Hercynius aves gignit, quarum pinnae per 

 obscurum emicant et interlucent, quamvis densa nox 

 denset tenebras." It is probable that he was not 

 unacquainted with Pliny's works. 



The first work solely devoted to luminous animals 

 was written in 1555 by Conrad Gessner : " De 

 raribus et admirandis herbis, quae sive quod noctu 

 luceant,sive quod alias ob causas lunariae nominantur, 

 et obiter de aliis etiam rebus, quae in tenebris lucent." 

 He speaks of plants and grass shining at night, and 

 seems to have an obscure idea of the origin of this 

 phenomenon, which he calls " res naturae luscentes." 



Finally, in 1647, Thomas Bartholin published his 

 great work, " De luce animalium." This is a com- 

 pilation, in three volumes, of observed (and some 

 problematical) cases of luminous animals. The third 

 book is entirely devoted to birds, and in it are 

 mentioned the Phoenix, the birds of Diomedes, the 

 " Incendiaria avis," which set on fire any tree or 

 house on which it perched ; the cock " cum luce 

 consensum alit," whose feathers had robbed from 

 the sun their brilliant metallic shine. 



But among these quaint beliefs one finds observa- 

 tions very probably true. In 1641, at Montpellier, 

 in France, during a short period of famine, many 

 fowls were brought to market. Several of these 

 birds attracted wide attention by their unmistakable 

 phosphorescence, and Henri de Bourbon, Prince de 

 Conde, was called to admire them. A cock was 

 killed "who shone on all parts of his body with a 

 remarkably strong light," " veram totius corporis 

 lucem . . . aperte exserint." The same year, at 

 Montebello, according to the author, there was a 

 hen which " shone like a ball of white fire." And 

 Thomas Bartholin, comparing these two birds, 

 ingeniously adds : " It is a pity that the cock did 

 not meet the hen ; for we might then have obtained 

 a breed of incandescent fowls." 



A SIMPLE METHOD OF DIFFERENTIATION BETWEEN MALTOSE 

 AND LACTOSE IN THE SOLID STATE. . 



A solid is given which reduces Fehling's Solution and does 

 not reduce Barfoed's Solution. The solid must be either 

 Lactose or Maltose. 



(1) Take some of the solid and place it in a clean dry test 



tube. 



(2) Add from 5 c.c. to 10 c.c. of absolute alcohol and shake 



well. 



[The alcohol should not be heated as Lactose is sparingly 

 soluble in warm alcohol and might give an erronous result, j 



(3) Then filter through a clean, dry filter funnel and receive 



the filtrate into an evaporating dish. 



(4) Evaporate the filtrate on a water-bath nearly to dryness, 



(5) To the filtrate then add a few c.c.'s of diluted Fehling's 



Solution and warm. 



[Before adding the Fehling's Solution a sample should be 



tested to see that it does not reduce of its own 



account.] 



(6) If reduction takes place, Maltose is present ; if no 



reduction, Lactose. 

 This differentiation can be carried out within the space of a 

 few minutes with quite a small amount of solid and with very 

 little apparatus. It is very useful when sugar is mixed with 

 a protein which will prevent one from obtaining an osazone 

 or a polariscope reading. 



The London Hospital, 



VICTOR FELDMAN, 



