October, 1902.] 



KNOWLEDGE 



235 



colours and so scatter a white lig;bt. lu its embrace also, 

 each snowflake as it lies upon the ground, holds a tiny 

 supply of air, and it is this circumstance that makes the 

 snow so bad a conductor of heat. Snow then in regard to 

 the earth and the atmosphere acts as a buffer state, so 

 that it i>asses no heat down from above and allows none 

 to travel upwards from below. 



Further, not only is snow of interest in the manner of 

 its l>ii-th and in resiwct of its sojourn on the earth, but its 

 actions are no less entertaining when it melts. In passing 

 it may be observed that one foot of snow is considered to 

 be equal to ten or twelve inches of rain. When, there- 

 fore, snow is on the ground to the depth of several feet 

 there is an enormous cjuantity of moisture held iu 

 suspension. It is not surprising then that when a sudden 

 thaw sets in, the water courses and rivers are unable to 

 carry off the melting snow, and that floods result. At 

 times, too, it will happen that the ground in the neigh- 

 bourhood of fallen snow is frozen hard, so that as the 

 snow melts it rushes impetuously onwards, disastrous 

 floods being ag-ain produced. When the snow disperses 

 iu orderly fashion it percolates through the ground, and 

 it will readily be u7iderstood that as the cold icy water 

 passes downwards notable modifications occur iu the 

 temperature of the soil. At such times undrained laud 

 becomes saturated with the chilly water, and for this and 

 other reasons it has been observed that the effect of 

 draining land is the same as if it bad been removed one 

 hundred miles to the southward. It is not, therefore, 

 surprising that in many countries considerable attention 

 is given to the work of observing the snow, so that ample 

 warning may be given to those whom it may concern of 

 the time when it is beginning to melt. 



Both when on the ground and when it melts it will 

 therefore be seen that snow is constantly modifying the 

 temperature of its surroundings. On the winds also 

 which blow to and from the snow-covered areas these 

 chauges have also their effects, so that in studying 

 climatic conditions it is imperative to know the times and 

 seasons when a given locality is covered with snow. As 

 already mentioned, to follow the biography of a snowflake 

 to the end, something should be said concerning glaciers 

 and icebergs ; but it is sufficient for jsresent purposes to 

 call attention to them, vrith the observation that they 

 were built bv the snowflakes. 



'are red or white, warranting the conclusion that these 

 colours are attractive to flies, which .lilect putrid sub- 

 stances. For this reason the Phalloidi are sometimes 

 designated the " Flowering Fungi." This is the light in 

 which Mr. Fulton also views the colours of the Amanitas, 

 IMyccnas and a number of the smaller agarics. Even the 

 .odour of putrefaction itself, he thinks, may be meant to 



VEGETABLE MIMICRY AND 

 HOMOMORPHISM.-V. 



By Rev. Alex. S. Wilson, m.a., b.sc. 



Thp; resemblance of Aseror Junghu to a sea^anemone was 

 referred to in a previous article; this fungus attains a 

 diameter of about a foot, is conspicuously coloured, and 

 like Phallus, emits a foetid odour ; the gleba at its mar- 

 gins splits up into long narrow segments, which closely 

 con-espond to the tentacles of the zoophyte. The plant 

 is a native of Java. Another remarkable member of the 

 same family is the tropical Dictyophora, which is not 

 unlike the common stinkhorn in shape, but is surrounded 

 by a delicate white network which hangs expanded below 

 the cap like a crinoline. This appendage, like the white 

 corolla of a night-flowering plant, increases the con- 

 spicuousness of the fungus after dark. The PhaUoidi 

 occupy a somewhat exceptional position among fungi. 

 Only some seven or eight per cent, of agarics, as Mr. 

 Wemyss Fulton points out, are attractively coloured, 

 seventy-four per cent, being brown, slaty or black. 

 Ninety-one per cent, of the Phalloidi on the other hand, 



FlO. 22. — Dictyophora, u 

 Fio. 21. — Aserijc, an anemone-like fungus. flonering fungus. 



atti-act flies which aid in the dispersion of putrefactive 

 bacteria. Some of the marsh bacteria give rise to a jelly 

 which floats as scum on pools and ditches. The beautiful 

 rose-pinlv tint of this jelly which is full of these 

 organisms may not improbably also be of use in pro- 

 moting their dispersion. The attractive characters 

 observed in fungi as a whole remind us of those flowers 

 which are adapted to the visits of flies, beetles and other 

 shoi-t>lipped insects. Gaily attired insects like the drone- 

 flies manifest a preference for the more handsome 

 blossoms, and are the most frequent visitors of the saxi- 

 frages, speedwells and forget-me-nots. The beautiful 

 amethyst Clavaria seen amidst its sui-rounding of moss 

 impresses the observer with the idea that this fungus 

 lays itself out to attract the same class of visitors. Insects 

 which themselves emit an odour likewise manifest a 

 fondness for strongly-smelling flowers; the odoriferous 

 bee Prosopis, for example, shows marked partiality for 

 the strongly-scented flowers of rue and mignonette. The 

 ofi'ensive odours of the PhaUoidi, though specially 

 attractive to flies, are in all probability repugnant to 

 ruminants. 



Numerous examples of interfungal resemblance have 

 been described, and though most of these may be merely 

 homomorphic, it is highly probable that at least some 

 of them may be truly mimetic. Many years ago Mr. 

 Worthington Smith directed attention to three British 

 fungi which so closely resemble certain common species 

 that minute examination is necessary to detect the 

 difference. One of the species thus copied is bitter and 

 nauseous, so that possibly the rarer kinds escape dis- 

 covery by being mistaken for distasteful species. At least 

 twenty species might be named, each of them closely 

 simulated by another species. Dr. Plowright gives a list 

 of twelve edible fungi, each imitated by one or more 

 poisonous species. The Caesarian agaric, esteemed a 

 delicacy in Italy, is copied by the poisonous amanita, or 

 vice versa, for it is not always possible to say which is 

 the original and which the copy ; the common mushroom 

 has at least three imitators with poisonous properties — 

 Jff. me!f,.yiermus. Ag. fastihi/is, and Ag. Taylnri ; one 

 can easily understand how fatal mistakes occur. Some 

 of these resembling fungi are no doubt closely related, 

 but in others the relationship is more remote, as in the 

 case of a small agaric, referred to by Dr. Cooke, which 



