110 



KNOWLEDGE. 



March, 1911. 



In the .\nlarctic, red-snow appears to be less coniinon than 

 in the North Polar region. The Shackleton Expedition did 

 not find any for certain, but some members saw snow dis- 

 coloured with what they supposed to be a red Rotifer common 

 there. Bruce's E.\pedition found a little of it, but the only 

 record I know is in Charcot's preliminary report of his last 

 Expedition (1910). The naturalist of that expedition, M. 

 Gain, informs me in a letter that they found both red and 

 green snow, the former in considerable quantity, the latter 

 forming extensive meadows (" prairies "). 



What is red-snow ? As to the colour of it, is it so very 

 bright ? Perhaps we who have not seen it expect too much ! 

 Some describe it as blood-red or crimson ; others say it is a 

 dull purple: Darwin noticed the footprints of his mules stained 

 a pale red, and the snow was only coloured where it had 

 thawed rapidly or had been crushed. Sir Philip Brocklehurst, 

 who saw our only supposed red-snow, tells me it was a very 

 dingy yellow. 



Red-snow has been almost universally attributed to a 

 supposed Alga, best known as Protococciis nivalis, though 

 it has borne many names, and is now officially recognized as 

 Spliacrclla nii'alis. It is described as consisting of spherical 

 cells, about a one-thousandth part of an inch in diameter, 

 with a thickish cell-wall, and the protoplasmic contents 



Figure 3. 



Spliacrclli! iiii'dlis. two clusters and two free swimming 



cells, the latter are marl;rd 4. 



permeated with chlorophyll, which is, however, completely 

 masked by the red pigment haematochrome. In the growing 

 season the cells enlarge and divide, usually into four daughter- 

 cells, which then separate, take an oval form, and swim about 

 by means of two fiagella, which are extensions of the proto- 

 plasm projected through the envelope. 



It has been so little suspected that any organism but 

 Protococcus nivalis could produce red-snow, that one may 

 suppose it has sometimes been recorded as that species, 

 without careful examination. Such was the view of Vogt, 

 who accompanied Agassiz on his Alpine journeys. 



Shuttleworth, in 1839, first suggested that other species 

 might participate in making the red-snow. 



Vogt (1840) made the remarkable discovery that his samples 

 of red-snow contained a Bdelloid rotifer in abundance. He 

 found associated with the rotifer some smooth and some 

 warted globules, which he satisfied himself were its eggs, and 

 he rather hurriedly concludes that there is probably no 

 Protococcus nivalis in existence, the name having been 

 given to rotifer eggs ! Those globules of Vogt's are unlike 

 any known eggs of Bdellnids. and I am sure he was wrong 

 about them. 



Vogt is not the only authority for the pi-eseuce of rotifers in 

 red-snow. Lagerheim, in 1892, found a Bdelloid in red-snow 

 in Ecuador. He identified it as related to Pliilodina roseola, 

 which is the same species as Vogt supposed his animal to be. 



Now, although the Shackleton Expedition found no indubit- 

 able red-snow, we found abundance of red rotifers, which 

 increased with prodigious rapidity and formed conspicuous 

 blood-red stains on stones at the margins of lakes. I named it 

 Philodina grcgaria. 



Vogt gives a very good figure of his supposed Pliilnduia 

 roseola, and the spurs are of such a form that Ehrenberg 

 doubted the identification. These spurs are very similar 

 to those of P. grcgaria. The similar habitat gives colour 

 to the suggestion that they are identical. The ."Mpine rotifer, 

 living on the surface of snow, must become active at just 



about the melting-point temperature. — /-".^^rc'^'ifr/if lives frozen 

 in ice for years, and resumes activity whenever the ice melts. 



It is now admitted that, while Sphaerclla nivalis may be 

 the connnonest cause of red-snow% animals of various kinds 

 may take part in producing the phenomenon. M. Gain, of the 

 Charcot Expedition, makes the latest addition to the list, as he 

 tells me he found reddish mites fairly plentiful in the Antarctic 

 red-snow. There is probably a considerable fauna of red-snow. 



What is the significance of the red colour of so many 

 animals which li\'e on the surface of snow ? Has it a 

 physiological function in relation to light, enabling the animal 

 to absorb the rays, w-hich will just make life possible in that 

 inhospitable situation ? It is noticeable that the red colour 

 of the rotifers, both .Alpine and Polar, is confined to the 

 stomach. 



There is a tendency, even in science, to reason from 

 insufficient data to erroneous conclusions — "jumping to a 

 conclusion," as it is termed in unscientific language. Let us 

 take warning from some of the facts connected with red-snow. 

 Vogt affords us an example of the danger, in his observations on 

 the supposed eggs of the rotifer of red-snow. He watched 

 till he observed a rotifer " deposit " one of the globules. If 

 this were sufficient evidence, we could soon find such 

 marvellous instances of alternation of generations as would 

 rival the fabled origin of the Barnacle Goose. Had Vogt 

 begun at the other end and waited for an egg to hatch, he 

 would, perhaps, have reached another conclusion. 



Red organisms are common enough apart from red-snow, 

 and there is no need to assume that all the red organisms 

 found in that situation have their red colour in virtue of the 

 association. Vogt includes among his animals of the red- 

 snow a Water- Bear with two claws, which he refers to as 

 Arctiscon and Macrobiotns, but the number of claws and 

 the red colour make it pretty certain that it was a larval 

 Echiniscns. Ehrenberg got several kinds of Echiniscns 

 high up (11,138 feet) on Monte Rosa. It seems a reasonable 

 supposition that the colour of these animals has a special 

 relation to a life among snow, but so far from this being the 

 case, it is the normal colour in this extensive genus, in 

 species living in all sorts of situations. One of the brightest 

 red species inhabits .Australia, where red-snow is little likely 

 to occur. 



Ehrenberg found on Monte Rosa, along with ihu Echi)iisci, 

 a bright red rotifer, which he named Callidina scarlatina. 

 It was found dried up, like pink dust, and, I believe, scattered 

 over the snow. But Callidina scarlatina is not specially 

 addicted to a life on the snow or even on mountain-tops. If 

 Mr. Bryce's identification is right, it is a familiar species among 

 hepatics growing on trees, in shady glens and similar places. 



As to Sphaerclla nivalis itself, the Alga of red-snow, I 

 find upon enquiry that it is a flagellate Infusorian, related to 

 that very energetic plant-animal, the Globe-animalcule. Volvo.x. 

 claimed alike by zoologists and botanists. If the flagellates 

 are conceded to zoology, then all the organisms of the red- 

 snow are animals. , ,.,m,,, .. r-ucr- -c-vc 

 James Murray, F.R.S.E., F.Z.S. 



MICRO-SLIDES ILLUSTRATING MITOSIS.— Every 



student of Cytology appreciates the difficulties attending the 

 preparation of slides illustrating the phenomena of nuclear 

 division. We have received from Mr. C. Baker, 244, High 

 Holborn, a sample slide showing mitosis in all phases, as 

 exhibited in the growing point of the root of Liliuni. His list 

 of slides also includes the root-tip of hyacinth and onion, 

 and the testes of the newt showing the developing spermatozoa. 

 We have received a selection of slides from Mr. H. 

 (iunnery, Acomb, York. He has specially devoted himself to 

 the preparation of slides illustrating the phases of development 

 in the embryo-sac and pollen mother-cells of Liliuni spp. 

 The slides we have examined are very good indeed. Special 

 mention may be made of one, showing the embryo-sac 

 containing two daughter-nuclei resulting from the first division 

 of the nucleus of the megaspore. Mr. Gunnery has also sent 

 for examination sets of botanical .slides, designed to meet the 

 requirements of the Intermediate Science and Board of 

 I-Mucation Examinations. All the types are well illustrated in 

 these sets, which are very reasonable in price. 



