254 On Coalescence of Amceboid Cells into Plasmodia. [Mar. 18. 



It is impossible to avoid comparing the above- described unions of 

 amoeboid cells with those occurring in the ordinary life-history of the 

 Myxomycetes,* and the resemblance is so complete that it seems not 

 only convenient, but necessary to extend the term plasmodium to the 

 former. 



The formation of plasmodia was at first supposed to be peculiar to 

 the Myxomycetes, but several Rhizopods (Microgromia, Bhapliidiophrys, 

 Phonergates, &c.) have been described, in which a more or less com- 

 plete cell-fusion has been observed, or perhaps, as I am disposed to 

 think, cell-fusion has been more or less completely observed. 



After comparing the descriptions and drawings of these formsj (see 

 Buck's figures of Phonergates, copied in the Plate, figs. 30 — 33) with 

 those of uniting corpuscles already given, the identity of the process 

 of coalescence in the two cases with each other, and with that of a 

 Myxomycete, will be sufficiently obvious. 



Finally, although much further observation is desirable, alike upon 

 the undifferentiated cells of Vertebrates and Invertebrates, and upon 

 the lowest plants and animals, it may be safely asserted that all the 

 evidence we possess points to the conclusion that the power of 

 coalescing with its fellows, under favourable circumstances, to form a 

 Plasmodium, is at any rate a very widely-spread, if not a general pro- 

 perty of the amceboid cell. 



The observations were chiefly made last summer at the Scottish 

 Zoological Station at Stonehaven. 



EXPLANATION OF THE PLATE. 



Fig. 1. Corpuscles of perivisceral fluid of Lumbricus terrestris commencing to 

 unite. 



Figs. 2 — 9. Eight successive drawings of the same group of corpuscles (Pholas). 

 Figs. 10 — 12. Union of group of corpuscles (Patella vulgata).' 

 Figs. 13 — 14. Union of group of corpuscles (Buccinum undatum) . 

 Fig. 15. Coarsely granular corpuscles (Pagurus Bernhardus). 

 Fig. 16. Finely granular corpuscles of same animal. 



Fig. 17. Small plasmodium (Pagurus Bernhardus) formed from finely granular 

 corpuscles, and containing several coarsely granular corpuscles in its 

 interior. 



Figs. 18 — 23. Union of group of corpuscles (Carcinus Manas). 



Fig. 24. Group of coarsely and finely granular corpuscles of Cancer Pagurus. 



# Sachs. " A Textbook of Botany." De Bary. " Die Mycetozoons." "Zeitseh. f. 

 Wiss. Zool." Bd. X. 1860. 



f Pv. Hertwig. " Ueber Microgromia socialis, erne Colonie bildende Monathalamie 

 des siissen Wassers." " Archiv. f. Mikros. Anat." Bd. X. Taf. 1. 1874. 



L. Cienkowski. " Ueber einige Rhizopoden und verwandte Organismen." " Archiv. 

 f . Mikros. Anat." Bd. XII. 1876. 



E. Buck. "Einige Rhizopodenstudien." "Zeitseh. f. Wiss. Zool." Bd. XXX. 

 ] 878. Taf. 2. 



