62 
GEOLOGY OF THE FIRST DISTRICT. 
The author, after balancing the arguments of the two theories respecting the classification of this body, 
gave as his reasons for retaining them on the side of the animal kingdom, the following summary: 
1st. That while Closterium has a circulation of molecules greatly resembling that of plants, it has also 
a definite organ, unknown in the vegetable world, in which the active molecules appear to enjoy an 
independent motion, and the parietes of which appear capable of contracting upon its contents. 
2d. That the green gelatinous body is contained in a membranous envelope, which, while it is elastic, 
contracts also upon the action of certain reagents whose effects cannot be considered purely chemical. 
3d. The comparison of the supposed ova with cytoblasts and cells of plants, precludes the possibility 
of our considering them as the latter; while the appearance of a vitelline nucleus, transparent but molecular 
fluid, a chorion or shell, determines them as animal ova. It was shown to be impossible that these eggs 
had been deposited in the empty shell by other infusoria, or that they Avere the produce of some entozoon. 
4th. That while it Avas impossible to determine whether the vague motions of Closterium were volun¬ 
tary or not, yet the idea the author had formed of a suctorial apparatus, forbade his classing them with 
plants. 
Lastly, in no instance had the action of iodine produced its ordinary effects upon starch or vegetable 
matter, by coloring it violet or blue, although Meyen asserts it did in his trials. 
The author, therefore, concluded that Closterium must still be retained as an infusory animal, although 
it is more than doubtful whether it ought to rank with the polygastric families. 
Upon the above statements of Mr, Dalrymple, I venture to offer the following remarks. 
1. As to the siliceous nature of the carapace: Ehrenberg expressly states, (1. c. p. 446,) 
that “ the carapace can be burned and completely volatilized.” This statement of Ehrenberg, 
together with the undoubted flexibility of the covering of many of the Closteria, which I have 
often noticed as wholly unlike the brittle siliceous coverings of the Naviculas, and the fact 
that I have never found their coverings among the fossil Naviculse, although the living species 
of each genus occur abundantly together, all induce me to think the carapace of Closterium 
can scarely be siliceous. 
2. Motions apparently voluntary. These are easily seen: I have often been unable to 
sketch the form of a specimen by means of the camera lucida, as the body was constantly 
changing its position, and this too when certainly undisturbed by the motion of other animal¬ 
cules or any extraneous cause. Their power of locomotion may also be rendered apparent 
thus : If a portion of mud covered with Closteria is placed in a glass of water, exposed to 
light, and the Closteria are then buried in the mud, they will soon work their way to the sur¬ 
face, covering it again with a green stratum, which may be buried over and over again, with 
the same results. 
3. Presence of moving molecules in distinct cavities. These are easily seen; generally 
there is one such cavity in each extremity, as indicated in most of our figures of Closterium, 
(see Figs. 30 to 38, PI. 21,) but sometimes there are many such cavities ; at other times almost 
the whole interior appears filled with active molecules, as has already been stated (p. 15) is 
sometimes the case with Euastrum. In specimens where the cavities at the ends were very 
distinct, and which also showed very distinctly the circulation referred to by Mr. Dalrymple, 
I noticed that the form of the cavity containing the active molecules was constantly changing, 
