PROTEOMYXA. 915 



masses are cut off and left behind. From Archer's statement it appears 

 certain that Chlamydomyxa has the power of digesting such organisms as 

 Cosmarium which may be carried with the protoplasm into the cyst. 



Though there are undeniable resemblances between Labyrinthula and 

 Chlamydomyxa, yet there are certain differences which make it possible 

 that the two ought not to be classed together. In one the spindles are 

 nucleated cells, the matrix and tracks apparently a secretion. In the 

 other the spindles are non-nucleated, the tracks, the branches, and stem 

 from which they spring protoplasmic ; there are contractile vacuoles and 

 other organisms may serve as food *. 



Labyrinthula, Cienkowski, A. M. A. iii. 1867; cf. Q. J. M. xv. pp. 121-4. 

 Chlamydomyxa, Archer, Q. J. M. xv. 1875 ; Geddes, ibid. xxii. 1882 ; at Pontresina, 

 Ray Lankester, Nature, xxxiv. 1886, p. 408. 



PROTEOMYXA. 



The assemblage of forms, for the most part inhabitants of the fresh- 

 waters, gathered together under the designation Proteomyxa (Ray 

 Lankester), are characterised mainly by the negative feature that they 

 cannot be assigned with certainty to any of the foregoing classes ; nor 

 is it possible to frame any satisfactory and common definition of them as 

 a whole. The discovery of new forms, and a_better acquaintance with 

 some of those already known, will in time lead, without doubt, to their 

 dispersal. 



A certain number of Proteomyxans have a Heliozoon-like aspect, which 

 they may exchange for an irregular one ; they may be colonial or capable 

 of indefinite growth. Others have been grouped by Zopf as Monadineae. 

 The typical feature of these forms is that they have two kinds of cysts, 

 one (zoocyst) within which the organism breaks up into spores, the other 

 (sporocyst) within which it contracts, encysts perhaps again, but eventually, 

 assuming a spherical or oval shape and acquiring a membrane, passes into 

 the state of a resting spore or chlamydospore, usually single. The spores 

 originating from the zoocysts are either flagellulae s. zoospores, or amoe- 

 bulae; hence a subdivision of the Monadineae into the M. zoosporeae and the 

 M. azoosporeae. But in the M. zoosporeae, with the exception of Colpodella, 

 the zoospore passes into an amoebula which grows in size and finally encysts. 

 Fusion of Amoebae into plasmodia is known to occur in some instances ; 

 and, partly on the strength of this fact, and partly on account of the 



1 Ray Lankester is of an opinion that the spindles in the two genera above-described are really 

 nuclei. Q. J. M. xix. 1879, P- 4^1. 



3N2 



