$$ 4, 5. 21 
often be seer. the so-called organization of Ehrenberg’s Monadina and 
Volvocina. Until the fact that ciliated organs belong to both animals and 
vegetables was decided, the real place of many low organisms had to 
remain undetermined.“ However, notwithstanding their free motion from 
place to place by means of cilia, the vegetable nature of many organisms 
seemed clearly indicated by the rigid, non-contractile character of their 
forms. It is from a misapprehension of the true nature of these facts, that 
some modern naturalists have denied the existence of limits between the 
two kingdoms. 
With Bacillareee and Diatomacez, this question has another aspect. 
Many of these organisms have been taken for animals from their so-called 
voluntary movements, which truly entirely want the character of volition. 
In the movements of the rigid Diatomaceze, for instance, the whole plant has 
oscillatory motions like a magnetic needle, at the same time slightly 
changing its place forward and backward. When small floating particles 
come in contact with such an organism, they immediately assume the 
same motion. This may be well observed with the Oscillatoria. There 
are here, undoubtedly, no ciliary organs; in fact, they could not, if pres- 
ent, produce this kind of motion. According to Ehrenberg,® the Naviculz 
can protrude ciliary locomotive organs through openings of their carapace ; 
but this has not been observed by other naturalists. 
4 
INFUSORIA AND RHIZOPODA. 
§ 4. 
The Rhizopoda, whose internal structure is as yet imperfectly known, 
are closely allied to the Infusoria. Like these last, their bodies are cellu- 
lar, containing nuclear corpuscles, but no system of distinct organs. These 
two classes of Protozoa differ, however, in their external form, and the 
structure of their locomotive organs. The body of the Infusoria, notwith- 
standing its contractility, has a definite form, and moves chiefly by means 
of vibratile organs. That of the Rhizopoda, on the other hand, although 
equally contractile, has no definite form; their movements also are not 
due to ciliated organs, but to a change of the form of the body by various 
prolongations and digitations. 
§ 5. 
Owing to the present incomplete details upon the organization of these 
animals, little can here be said about them; and therefore, instead of 
devoting to them a separate chapter, it will be proper to treat of them 
with the Infusoria in general. 
As:the division of the Polygastric Infusoria, by Ehrenberg, into two 
Also, Kitzing, Ueber die Verwandlung der 
4 Asan may be d the various 
Infusorien in niedere Algenformen. Nordhausen, 
and dissimilar opinions of naturalists upon the 
question of the animal or vegetable nature of the 
“red snow ;” a question upon which Flotow, 
after the most careful. studies, is still undecided. 
See Flotow, “Ueber Haematococcus pluvialis,” 
in Nov. Act. Acad. Leop. Carol, vol. XX. part ii. 
. 18. 
e 5 See Unger, Die Pflanze im Momente der 
Thierwerdung. Wien. 1843. 
1844. 
In an academic paper (Dissertatio de finibus 
inter regnum animale et vegetabile constituendis, 
Erlangae, 1844), I have attempted to show that this 
confusion between the two kingdoms does not exist. 
6 Abhandl der Akad der Wissen- 
schaften zu Berlin, 1836, p. 134, Taf. I. fig. 19, and 
1839, p. 102, Taf. IV. fig. 5. 
