320 M. M. Mercatr 
O. intestinalis (Text Fig. XIII, A). A late stage of division was 
observed in Buocu’s preparations by his friend “Herr Oberprediger 
Herpst” and was interpreted by Buiocu as copulation (upper two 
animals of Text Fig. XIII, A). As the animals were united by their 
pointed ends, these were regarded as posterior and it was assumed 
that the mouths must be at the opposite broader ends. The second 
form, Chaos, may possibly have been O. ranarum (Text Fig. XIII, B 
and C). Buocn’s artist saw many small particles come out of the 
posterior (?) end of a quiet individual, which soon died, phenomena 
which Buocu interpreted as the birth of young. [Doubtless the 
animal was going to pieces.| 
Text Fig. XIII. 
Buocu’s figures of Opalina (?). A, three of his nine figures of “Hirudo intestinalis 
(der Eingeweideblutigel)”’. The upper pair [in a late stage of division] show what 
he interpreted as copulation. B, two of his seven figures of “Chaos intestinalis 
cordiformis (das herzfirmige Infusionstierchen)”. C, an animal of the same species 
“giving birth to young’. Band C, probably represent Balantidium and not Opalina. 
GézE (1782, p. 429 —433, Taf. 34), in the same year, makes a 
more important contribution to our knowledge of Opalina. He says 
Chaos includes several sorts of intestinal worms which are found in 
the “Landfrosch” {Rana temporaria], the “ Wasserfrosch” [R. esculenta], 
the “Mittelfrosch’’ | Bombinator pachypus?|, in ~Landkréten” | Bufo 
cinereus ?| and “Wasserkréten’” | Pelobates fuscus?|. He says they live 
naturally in the recta of these amphibia and have not merely 
wandered in from the water because: 1) they are never found in 
water; 2) they are found in land-toads as well as in water-toads; 
3) they are found only in the anterior end of the rectum, just 
behind the constriction which separates it from the small intestine, 
never in the small intestine or in the back part of the rectum; 
4) one finds three or four species always of constant shape; 5) if 
frogs are kept a quarter of a year in water the rectum becomes 
entirely empty of the animals, and still none of these animals are 
found in the water. though many other Jnfusoria are present. He 
says that one finds frogs or toads with either very few or none of 
the Chaos in the recta, that the little animals are more abundant 
