X. 



FURTHER NOTES OX THE MYCETOZOA, WITH A LIST OF 

 SPECIES FROM HERTS, EEDS, AND BUCKS. 



By James Saunders. 



A Lecture delivered at Watford, 19<A December, 1893. 



PLATES IV AND V. 



There is not a ^voodland, bosky dell, or more extended forest 

 but teems with life. From the leafy canopy overhead, with its 

 winged denizens, away down the rough stems of oak and ash, 

 with their lichens and liverworts, to the spreading moss-covered, 

 roots, exists a multitude of living beings ; and this not only in 

 one spot, for such scenes might be multiplied indefinitely. 



In any part of the world — from Canada to Ceylon, from England 

 to I^ew Zealand — would be found in such circumstances innumerable 

 forms of life. These all agree in certain fundamental points. 

 They start from a living cell, they are built up of cells, and every 

 cell, when in activity, contains protoplasm. Do not these facts 

 suggest that they form part of one organic whole ? — that con- 

 sequently there is no sharp line of demarcation between the animal 

 and vegetable world ? — that there are points at which these two 

 kingdoms coalesce, and that all creatures have descended from a 

 few primordial types, or possibly from but one ? 



On the border-land between the two realms of the natural world 

 may be placed the creatures now under consideration. In what 

 may be taken as the initial stage of their life, they exist as minute 

 spores, many of which float in the air, and are distributed by 

 the wind. When these fall on favourable situations, such as rotten 

 wood or decayed leaves, the covering of the spore becomes 

 moistened, and the protoplasm within bursts its way thi-ough. 

 These amoebifonn bodies are usually elongated or pear-shaped, with 

 a minute cilium at the narrow end, and are known as "swarm 

 cells." They have the power of locomotion, and, like the Amoeba?, 

 frequently assume various shapes, their changes and movements 

 being presumably effected in the search for food. They have been 

 seen by careful observers, notably by Mr. A. Lister, to feed on 

 Bacteria, which they surround by a digestive vacuole, these 

 microbes being gradually absorbed xmtil no trace of them can be 

 seen. It is probable that the ofiice of the Mycetozoa in the 

 economy of nature is similar to that of the white blood-coi'puscles 

 of the human body, in tliat they destroy germs of disease. 



After a brief period of independent existence they lose their cilia 

 and unite to form what is known as plasmodium, which has the 

 power of creeping, when favourably circumstanced, and exercises 

 this power to obtain sustenance. During this stage there is con- 

 siderable increase in size ; the plasmodium grows upon what it 

 absorbs, be this decayed vegetation or minute forms of life. During 

 the mobile stage of existence, different genera and species exhibit 



VOL. VIII. PART III. 



