$ 23. INFUSORIA AND RHIZOPODA. as 
It is not rare that a variable number of these round nuclei, arranged 1 in 
a row, traverse the body in a tortuous manner. This is so in Stentor 
coeruleus and polymorphus, in Spirostomum ambiguum, and in Trachelius 
moniliger. In many instances the nucleus has the form of an elongated 
band, which is slightly curved in Vorticella convalluria, Epistylis leucoa, 
Prarodan niveus and Bursaria truncatella. In Stentor Reselii, it is 
spiral, and in Euplotes patella and Trichodina mitra, it is shaped like a 
horse-shoe. In Lozodes bursuaria, it is kidney-form, and encloses in one of 
its extremities a small corpuscle (nucleolus). 
The round nucleus of Euglena viridis has in its centre a transparent 
dot. In Chilodon enicaltlats, the nucleolus has a similar dot, and thus the 
nucleus as a whole resembles a cell. 
§ 232. |: 
These nuclei, which make Infusoria resemble cells, deserve a special 
attention, since they do not,die’ with the animal. Thus the nucleus of 
Euglena viridis, which, according to Ehrenberg,” is globular when dying, 
and surrounded by a kind of cyst, remains unchanged a long time, or even 
inereases in size, having no appearance of a dead body. It may be that 
the life of this animal, under these circumstances, is not finished, but only 
assumes another form.” 
1 Loe. cit. p. 110. That the nucleus contained in Infusoria plays an 
2 Perhaps this nucleus, of which the animal is 
only a temporary envelope, is ultimately developed 
into a particular animal. Indeed, perhaps this 
species, as well as many others, are only the larval 
states of other animals, whose metamorphoses are 
yet unknown. It may properly be asked, if this 
nucleus has not, relative to the body containing it, 
the same signification as have the tubulous larve 
of Monostomum mutabile (see below) to the em- 
bryos they surround. 
important part in the propagation of those animal- 
cules, is supported also by a recent observation of 
Focke, who witnessed the development of several 
young individuals in the nucleus of Loxodes bur- 
saria. See Amtl. Bericht tiber die 22 tr. Versaaml. 
deutsch. Naturforscher. in Bremen, Abth. ii. p- 
110. 
