96 TflE VICTORIAN NA^rUIlALlST. 



Since they are living organisms, the first point to be discussed is, 

 do they belong to the animal or the vegetable kingdom ? and the 

 answer to that question will show that they partake of the nature 

 of both, and yet, strictly speaking, belong to neither. In fact they 

 lie on the borderland of both kingdoms, and consequently have 

 a botanical and a zoological aspect. It is not my intention to 

 quote authorities this evening, but to consider the leading features 

 presented by this group of organisms, and then draw such con- 

 clusions as the facts warrant. 



There is something in a name in this case, for the nanie chosen 

 will indicate a leaning either to one side or the other. 

 Myxogastres was the name given to the group by Fries in 

 1829, as he considered that they had some connection with 

 the group of fungi known as Gastromycetes, but that view is 

 now given up. Wallroth, in 1833, used ^^^ name Myxomycetes, 

 or slime-fungi, and in 1859 De Bary introduced the term 

 Mycetozoa, or fungus-animals, to indicate their relationship with 

 the lower forms of animal life; so that it becomes a question as to 

 which name is the most appropriate, Myxomycete or Mycetozoon. 



Apart from any views we may hold as to their nature, they have 

 briefly the following life-history in typical cases : — 



1. Starting with the spore^ which is produced in a sporangium, 

 this produces on germination — 



2. A Swarm-spore, which is typically pear-shaped, and provided 

 with a cilium by means of which it can move about. After a time 

 this cilium is drawn into the body, and now it becomes an 

 amoeboid body — 



3. Myxamceha, as it is termed, and capable of creeping about. 

 When two of these meet their protoplasm can flow together into 

 a single mass, and a number of these uniting constitute the last 

 stage of all — 



4. Plasmodium, a mass of naked protoplasm, which still retains 

 the power of movement. This last process is sometimes spoken 

 of as multiple conjugation, but the nuclei do not fuse. Finally 

 the sporangia are produced, with their contained spores, and the 

 life cycle is completed. 



Let us now see in the first place on what characters their 

 animal nature is based : — 



1. Power oj movement. — At certain stages of their existence they 

 can either creep or swim, and no doubt but the amoeboid move- 

 ment is an animal characteristic. It is well known, however, that 

 there are undoubted plants which at one stage of their existence 

 are capable of free movement, and have the " animal " motion 

 characteristic of infusoria in water, as in the swarm-spores of 

 Ulothrix, or the zoogonidia of White Rust (Cystopus), for instance, 

 so that this character may be dismissed as irrelevant. 



2. Power of absorbing and digesting solid nutriment. — This is a 

 character not known among recognized plants, and both the plas- 



