2S6 W. ARCHER* 



condition of a little protoplasm-mass — remaining all through 

 their existence " beings without organs " — these are Hackel's 

 " Monera." 



A still greater number, however, reach a higher develop- 

 ment, producing in their interior a nucleus, Avith its nu- 

 cleolus. This body where it occurs maintains a remarkable 

 constancy of its form. A clear vesicle, whose contents 

 coagulate only sparingly or not at all on the application of 

 acetic acid (nucleus), encloses a body either of a simple oval 

 figure or divided into several portions and of pale bluish 

 tint, which, under dilute acetic acid, coagulates in a darkly- 

 granular manner, in strong solutions, swelling up, without, 

 however, becoming dissolved (nucleolus). The outermost 

 zone of the nucleus frequently forms a membranous layer. 



Hollow spaces (vacuoles) filled with fluid are very preva- 

 lent in the protoplasm ; they are present either in changeable 

 number and in any position, or they are restricted to definite 

 parts of the body and then limited in number. They often 

 originate and disappear periodically — an alternation which 

 proceeds, in the last-mentioned cases constantly, in the first 

 frequently, with the appearance of rhythmical contractions. 

 Under all circumstances these represent nothing more than 

 vacuities in the protoplasm, filled with fluid, and they are 

 quite destitute of any definite wall. 



The "skeleton^' (when present) is formed of a number 

 of isolated spines and spicules of the most different form 

 and arrangement, or of a single connected piece of varied 

 form. A greater degree of firmness and resistance in the 

 skeleton parts is arrived at by depositions of mineral con- 

 stituents, chiefly of carbonate of lime or silex ; more rarely 

 foreign bodies, such as minute fragments of silex or of diatoms 

 are cemented on the shell. 



The same simplicity, characteristic of the group, shows 

 itself also in the development — division only of the total 

 body-mass serving to multiplication. Any special organ 

 destined thereto is not present : at least the interpretation of 

 the nucleus as a brood-cell for daughter-orga^lisms, put for- 

 Avard by many, is not supported by any certain or connected 

 observation. In their simple development-cycle encysting 

 has a wide-spread place. The organism assumes a globular 

 shape, and excretes a simple or multi-laminated coat. After 

 some time the body breaks up into two or several portions, 

 boring through the wall and each assuming the form of the 

 mother-organism. The interpolation into the cycle of their 

 life-history of the encysting process Avould seem justly to be 

 considered as a condition only subsequently, as it were. 



