THE INTESTINAL PROTOZOA OF FROGS AND TOADS. 937 
has been usually so described. Anyone who will take the 
trouble to watch an Octomitus continuously for several 
hours can convince himself of this. When the animal is 
moving quietly and has ceased to dart about, the axostyles 
invariably appear parallel with one another (see fig. 31). 
This crossing of the rods during active screw-like movements, 
moreover, negatives the suggestion of Prowazek that these 
structures, in O. intestinalis, are really not rods, but the 
sides of a tube seen in optical section. The axostyles have 
also been frequently interpreted as continuations of the caudal 
flagella (cf. Foa, etc.) 
I have described the nuclear apparatus as it appears to me 
most usually to exist.!. But there are other variations often 
met with. It is very commonly found that the two anterior 
pairs of granules are fused or superimposed, so that they can- 
not be made out clearly (cf. fig. 30). Many considerations 
have led me to believe, however, that the nuclear chromatin 
is really arranged in the three pairs of parts which I have 
described. A very striking confirmation is seen in a degene- 
rate form, which is not uncommon in old cultures (see fig. 37, 
Pl. 3). In this the nucleus has degenerated and broken up, 
but into three pairs of granules. These forms have died and 
east off their flagella. The nucleus has been resolved, I 
believe, into its component parts. 
Very many other degenerate forms have been encountered. 
I will here mention only one more, which is very striking m 
appearance. In this (see fig. 36) the nucleus has fragmented, 
and the fragments have run along the axostyles, so that they 
present the appearance of strings of beads. 
There is no cytostome and no contractile vacuole. 
Octomitus dujardini occurs in Rana temporaria, R. 
esculenta, and Bufo vulgaris, and is equally common in 
all of them. It occurs also in newts. 
1 It is worth noting the extraordinary way in which all the parts of 
the nucleus and its connections are paired, thus giving rise to a very 
well-marked bilateral symmetry. It is interesting, too, to compare this 
form with other similar forms, e.g. Lamblia (cf. Metzner [66]). 
