PROTOPLASM AND NUCLEUS. 



41 



Myxomycetes, some swarm-cells, e.g. of Faucheria, allow the skin to be recognised, 

 under sufficient magnifying power, as a hyaline edging; in the swarm-cells of Vaucheria 

 it is evidently striated radially when seen in section, just as some cell-walls are ; 

 Hofmeister (Handbuch, vol. L p. 25) found the same appearance in the plasmodia of 

 Mthalium. Probably this skin is nothing but the pure basis of the protoplasm itself 

 free from granules, of which the whole body is formed, but which is masked in 

 the interior by grains and granules. It follows that in the amoeboid movements of 

 Plasmodia the new extensions are always at first formed of the skin alone ; it is only 



Fig. 40. — B — G protoplasm from an injured filament of Vaucheria terrestris, slowly emerging in water, in different successive 

 conditions, at intervals of about five minutes; h the wall of the ruptured filament; i the protoplasm which still remains in the 

 filament ; a in B, C, D, and F, a ball of protoplasm detaching itself, forming vacuoles, then dissolving (in F)\ b a. branchlet of the 

 protoplasm from which the mass b' k detached, this mass isolated in D, dissolved in P; c and c' behave in a similar manner; 

 G shows the further changes of the part c" laF. A a freshly escaped mass of protoplasm, rounded off into a sphere, the chlorophyll- 

 granules lying all together in the inside; a hyaline layer of protoplasm envelopes the whole as a skin. 



when they increase in size that the interior granular substance makes its appearance 

 in them. This is more clearly the case in the masses of protoplasm that escape into 

 water from the injured filaments of Faucheria, which often instantly become rounded 

 into globular bodies, but not unfrequently show the amoeboid movement of plasmodia 



a later stage ; they are somewhat longer, the full extremity of each being terminated by a knob ; 

 'as development proceeds the cilia become longer and the knobs become smaller in proportion to the 

 increase in length, until the final hair-like form is reached. As long as the swarm-cell is in contact 

 with the mother-cell-walls, the cilia are closely adpressed to the surface of the ectoplasm, with their 

 apices directed forwards. The secretion of a cellulose envelope is closely and even inseparably con- 

 nected with the presence of an ectoplasmic layer. See Strasburger, Studieu iiber Protoplasma, Jena 

 1876; Vines in Quart. Journ. Micr. Sci. 1877, pp. 124-132.] 



