BOTANY These are sometimes so abundant that the straw looks as though whitened with hoar-frost. Another species, Fu/igo septica, known also as ' flowers of tan,' may occasionally be seen on the surface of straw-heaps. It appears as a yellowish white mass, and is sometimes so large as to be compared by casual observers with cauliflower heads. In some species the immature condition is different in colour from that of the mature. This is notably the case with some species of the genus Comatricba, which, upon emerging from the substratum, appear like minute white beads on hair-like black stalks. In a day or two the spor- angia turn to a dusky brown. Others again, as Lamproderma, look like minute black beads, which glisten as though covered with varnish. These when mature exhibit iridescent hues. A very generally distributed species (Lycogala miniatum), frequently seen in woods in early spring, finds a congenial habitat in decayed logs of wood. When immature it is of a lovely pink or crimson hue, which gradually changes to light brown on arriving at maturity. The heads are sessile, and range from the size of a pea to that of a hazel nut. Another form, known as Trichia persimilis, presents the appearance of a patch of sessile white beads, which when ripe change to a bright yellow. Their metamorphoses. In what may be regarded as the initial stage of their life-cycle the Mycetozoa exist as minute spores, usually spherical, each of which contains a speck of protoplasm ; or rather they should be regarded as minute particles of protoplasm which have invested them- selves with a covering of cellulose, usually ornamented with patterns which are constant according to the species. These spores are readily distributed by the wind, and when they fall in favourable situations the spore-covering is thrown off and the contained protoplasm assumes an amoeboid form. Eventually a number of these unite and form a plasmodium. This may consist of only a minute expansion, or it may extend to a foot or more in length, presenting the appearance of a network of motile streaming veins. The colour of this varies in different species and genera. It may be yellow as in Badbamia, grey or white as in Pbysarum, pink or rose as in Lycogala, and slate-colour as in Cribraria argillacea. The plasmo- dium may be regarded as the feeding-stage of the organism, and is so undifFerentiated in structure that any portion of it may become a foot, or a mouth, or a stomach, according to requirements. It presents also the phenomenon of circulation, which is of a most singular character. When examined microscopically, the granular contents are seen to flow in one direction for about a minute and a half; then follows a brief pause, after which the streaming motion is set up in the opposite direction ; and this alternate ebb and flow is continued until the organism undergoes a further change of form. The plasmodium-stage may be regarded as that in which conjugation takes place, as it is followed by the formation of spore-bearing organs. After continuing in this plastic state for an indefinite period, which may be for weeks or months, the plasmodium contracts itself into com- 77
