On Frenzel’s Mesozoon Salinella. 465 
LXVIII.— Critical Observations on Frenzel’s Mesozoon Sali- 
nella: a Biological Sketch. By Prof. StrerFAN APATHY*. 
IN the ‘ Zoologischer Anzeiger’ for 1891, no. 367, pp. 230 
et seg.t, and in the ‘ Biologisches Centralblatt,’ Bd, x1. 
pp- 577 et seq.t, Frenzel described a new animal, on which 
he bestowed the name Salinella§. The creature is a tube 
provided with two apertures—mouth and anus—and its wall 
consists of a SINGLE LAYER OF CELLS. The cells on the 
ventral surface are similar to one another and finely ciliate ; 
it is only around the mouth, which is not quite terminal in 
position, that certain of the cells are provided with stouter 
cilia. On the dorsal side the cells bear short sete instead of 
cilia. The surface of all the cells which is turned towards | 
the intestinal cavity is likewise finely ciliate. Food-particles 
are found in the intestine in a solid form. Frenzel is led to 
believe that intracellular digestion does not take place. 
By the discovery of Salinel/a our store of facts received a 
very material addition, since the creature in question, as it 
appears to me, serves to a certain extent to fill the gap 
between Volvox and Trichoplax. For the comprehension of 
the most primary forms of multicellular life Salinel/a seems 
more important than the Orthonectids and Dicyemids, in 
which we find a genealogical stage, certainly a very ancient 
one, at the best merely restored by parasitism as a fully- 
developed animal. 
A large number of questions of the highest biological 
importance can be connected with Salinella; but although in 
Salinella Frenzel furnishes an important contribution for our 
comparisons, he himself, in criticizing it and the problems 
connected with it, does not make sufficient use, for the pur- 
poses of comparison, of the store of facts already available. 
The result is that certain difficulties, which are indeed present, 
* Translated from the ‘Biologisches Centralblatt, xii, Bd., no. 4 (Feb. 
29, 1892), pp. 108-123. 
+ Ann. & Mag. Nat. Hist. ser. 6, no. 49, Jan. 1892, pp. 109-111, “A 
Multicellular Infusorian-like Animal.” 
t Ann. & Mag. Nat. Hist. doc. cit. pp. 79-84, “The Mesozoon Salinella.” 
§ Under the title ‘“ Untersuchungen iiber die mikroskopische Fauna 
Argentiniens,” Frenzel publishes a detailed description, with figures, in 
the last part of the ‘Archiv fiir Naturgeschichte’ (58 Jahrg., i. Bd., 
1 Heft, pp. 66-96, Taf. vii.). This was issued last December, but it did 
not come into my hands until later. In this paper Frenzel adds to his 
previous statements nothing that is essentially new ; I therefore consider 
it unnecessary to discuss it further at present. 
Ann. & Mag. N. Hist. Ser. 6. Vol. ix. 35 
