PROTOPLASM AND NUCLEUS. 



41 



the zygospores of Spirogyra (Fig. 6), and in many spores and pollen-grains^. In the 

 food-reservoirs of dry seeds {e.g. the cotyledons of peas and beans), the protoplasm 

 itself is often collected into small roundish grains, between which lie the grains of 

 starch; this condition of protoplasm will be further touched on hereafter. 



(b) Skin, Var.uoli, Mo'vement. Naked protoplasmic bodies, as the plasmodia of 

 the Myxomycetes, some swarm-spores, e. g. of Vaucheria, allow the skin to be re- 

 cognised, under sufficient magnifying power, as a hyaline edging; in the swarm- 

 spores of Vaucheria it is evidently striated radially in the optical section, just as 

 some cell- walls are ; Hofmeister (Handbuch, I. p, 25) found the same in the plas- 

 modia of iEthalium. Probably this skin is nothing but the pure original substance 



l-IG. 42— />>(; protoplasm from an injured sac of I'auchcrta Urrestris, slowly euierginif in water, in dilTerent successive conditions, 

 at intervals of about five minutes ; h the cell-wall of the ruptured sac ; i the part of the protoplasm which still remains in the sac ; 

 a in fi, C, D, and F, a ball of protoplasm detaching itself, forming vacuoli, then dissolving (in F); d a. branchlet of the protoplasm 

 from which the mass // is detached, this mass isolated in D, dissolved in F; c and d behave in a similar manner; G shows the 

 further changes of the part c" \n F. An freshly escaped mass of protoplasm, rounded off into a sphere, the chlorophyll-grains 

 lie all together in the inside ; hyaline protoplasm envelopes the whole as a skin. 



of the protoplasm itself free from granules, of which the whole body is formed ; 

 only the parts which lie most in the interior are permeated by grains and granules. 

 It follows that in the amoeba-like movements of the plasmodia the new processes are 

 always at first formed of the skin alone ; it is only 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 sacs of 

 Vaucheria, which often instantly become rounded into globular bodies, but not unfre- 

 quently show the amoeba-like movement of plasmodia for as much as half-an-hour or an 

 hour (Fig. 42). This interpretation of the skin is not at all opposed to the fact that 



^ J. Hanstein gives to the substances mingled with the true protoplasm and which undergo many 

 transformations, the collective name of ' Melaplasm.' (Bot. Zeilg. p. 710, 1868.) 



