MEMOIRS. 
Monograph of Monera. By Ernst Hackel. 
With Plates IX & X. 
( Continued from p. 42.) 
No nuclei or nucleus-like form could be perceived 
throughout the entire plasma body of the Protomyxa, nor 
contractile vesicles, if we understand by these, fixed organs 
which, although without a differentiated wall, still occupy defi- 
nite positions in the body. Nevertheless, a great number of 
vacuoli were dispersed through the body, as well in the 
central mass as in the thicker branches. These appeared in 
the form of paler and more circular spots (fig. 11, 11 v) of 
different sizes, the largest of 0 03 mm. diameter. If one 
observed the same vacuole for a little time, its dilatation 
and contraction, and its appearance and disappearance could 
be distinctly observed. The former as well as the latter 
occurred very slowly, and required from about two to three 
minutes in the largest. By contraction the size of the vacu- 
ole became smaller and smaller, at last the clear space 
entirely vanished ; and it appeared as if the yellowish-red 
plasma had flowed together over it. If the place w here the 
vacuole had vanished was watched, the vacuole would some- 
times be seen to reappear slowly in the same place. A paler 
point appeared which became slowly larger and larger ; it 
often exceeded its former boundary ; another time it did 
not attain to it. But very often the vacuole remained 
invisible, and instead of this one, one or more new vacuoli 
appeared in other places, some near and some very distant. 
Sometimes in the place of a large vanished vacuole ap- 
peared a number (ten to twenty) of small vacuoli in the 
neighbourhood, either irregularly scattered or grouped in 
a circle over the place of the vanished vacuole. All this 
shows that the contractile cavities in the body of the Proto- 
myxa are really vacuoli, i. e., wall-less cavities filled with a 
watery fluid in the middle of the homogeneous sarcode 
parenchyma, like those which also occur in many Rhizo- 
VOL. IX. NEW SER. H 
