DR. DUFFIN, ON PROTOPLASM. 207 
substance, but may only ensue when they have quitted the 
body of the animal. The lines of contact do not always 
totally disappear. These compound radii are always enclosed 
by a common sheath of the soft granular mass. Should the 
axes only unite outside the body, the soft coverings of each 
will coalesce, whilst the finer hyaline axes run side by side, 
without becoming agglomerated. Thus Actinophrys Hichhornit 
appears to contain in its pseudopodia both those substances 
that are found separately in Gromia oviformis and Dujardiniti. 
The application of artificial means further illustrates the 
structure of the pseudopodia of Actinophrys. If moderate 
pressure be exerted on the animal so as to flatten it, the 
pseudopodia will be slowly drawn back. The granular cortex 
melts together to little, spmdle-shaped nodules, and the pre- 
viously smooth fibre appears varicose. The fibre continues 
to retreat, and may become curved. Whenever one of the 
spindle-shaped aggregations of the cortical substance touches 
the surface of the animal, it flows in with a sudden jerk, as 
when one drop of fat is merged into another. This is quite 
decisive for the glutinous character of the material in ques- 
tion, and proves that a special membrane does not exist on 
the surface of the pseudopodia. Similar changes take place 
on the addition of very dilute acids and alkalies, solutions of 
strychnia and veratria, and under the influence of the mag- 
neto-electromotor. The influence of an elevated temperature 
closely resembles that of the agents just alluded to. Between 
35° and 38° C. the contraction of the pseudopodia begins. 
The soft granular cortical substance becomes aggregated into 
spindle-shaped masses on the surface of the axial thread. 
The pseudopodia retreat altogether, and the animal might be 
considered dead were it not for the slow progress of a few 
granules in the interior, and that no haziness of the sub- 
stance takes place. Schultze found Actinophrys Hichhorni 
to remain alive till 42° C. 
- It is remarkable with reference to Ktihne’s* investigations 
on the rigor mortis produced by heat, that even among in- 
vertebrate animals great varieties exist as to the period of its 
occurrence. Thus Vorticellz begin to die at 41° C.; Difflu- 
gia, Actinophrys, and Amoeba (radiosa, Ehrenb.), remain 
alive till 42° C. Anguilline, Turbellariz, Naiads, Rotifere, 
and Ostracodes, are in active life at 43° C.; and a few sam- 
ples even till 45° C. If we trace the pseudopodia of Actino- 
phrys Eichhornii to their roots on the surface of the darker 
nucleus, they will be observed to lose themselves in the walls 
* «Ueber die chemische Reizung d. Muskeln und Nerven,” Miiller’s 
‘Archiv,’ p. 315, 1860. 
