446 SECOND PART.- -MYCETOZOA. 



point under consideration presuppose on the one hand their connection with the Fungi 

 as something ascertained, and on the other hand in dealing with the affinities of 

 the Fungi so leaves the firm ground of definite facts for the regions of speculation, 

 that they cannot be admitted into a discussion which keeps close to facts. The view 

 lately promulgated by J. Klein in his treatise on Vampyrella is essentially the same as that 

 which would derive the Myxomycetes and the Chytridieac from a common stem lying 

 outside the series of Fungi. It sees the form, from which Myxomycetes, Chy- 

 tridieac and Rhizopods all descended, in the Vampyrellae which belong either to the 

 Rhizopod-type (or Hcliozoa-type) or to that of the Myxomycetes, but it can hardly be 

 said to have any foundation in facts ; it should have gone somewhat further back to 

 the Flagellatae, as has been suggested above. 



DOUBTFUL MYCETOZOA. 



Section CXXV. 1 here exclude from the ranks of the true Mycetozoa a few 

 forms or groups of forms, some of which have been occasionally mentioned in the 

 preceding sections. These forms so far as they are known have many points of 

 resemblance with the Mycetozoa, but either our knowledge of them is imperfect, or 

 else they depart so far in certain points from the typical Myxomycetes and Acrasieae, 

 that it is better to have their position in the system for the present undetermined. At 

 the same time we may properly give a brief enumeration and description of them in 

 this place. 



Bursulla erystallina, Sorokin, is, according to the author's account of it, a very 

 small Myxomycete growing on horses' dung, with an ovoid stalked sporangium 0.03 

 mm. in height, and forming eight spores by simultaneous division. The spores before 

 tiny become invested with a firm membrane escape from the swollen apex of the 

 sporangium in the form of swarm-cells without cilia but capable of amoeboid move- 

 ment, and subsequently coalesce in indefinite numbers and form plasmodia, which in 

 their turn become fashioned each into a single sporangium or into a group of several 

 sporangia according to their size. Sorokin saw no nucleus in the swarm-cells at the 

 ordinary vegetative temperature; on the other hand a nucleus was observed when the 

 sporangia were exposed to a very low temperature (as low as — 27 C). The develop- 

 ment was in other respects the same ; we may conclude therefore that the nuclei of 

 the swarm-cells had been overlooked in the first-mentioned case. We may venture 

 therefore a step further and assume that when a swarm-cell with a nucleus encounter^ 

 one which is supposed to be without a nucleus, the two coalesce into a cell which 

 forms a membrane and passes into a resting state as a kind of oospore; and that 

 after hibernation the protoplasm issues forth from the membrane and becomes 

 fashioned into an ordinary sporangium. This may in fact be simply a case of the 

 encystment of small plasmodia. Apart from the peculiar features which require 

 examination we may really have a small Myxomycete before us in Bursulla. 



The course of development in Haeckel's pelagic Protomyxa aurantiaca 

 entirely resembles that of a Myxomycete. ' Protoplasmic body, a plasmodium of an 

 orange-red colour, (always?) formed by coalescence of several swarm-spores, 0.5-1 

 mm. in diameter; with very many thick arborescently branched pseudopodia which 

 form a net-work by frequent anastomoses. Resting state, a spherical lepocytode with 

 a diameter of 0.15 mm., and a thick structureless envelope (cyst). Swarm-spores 



