KINGDOM OF PRIMITIVE FORMS.

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Fig. V represents the second group of the Protistic kingdom-the Amoeboida or Protoplasta. Here it will be observed we have advanced a step, and have attained to the dignity of a true cell, the Amoeba being a monocellular organism containing a nucleus. The mode of reproduction differs from that which obtains in the Monera, for although occurring by scissiparity or self-division, it is the nucleus itself which separates into two halves; the cell substance eventually divides, thus forming two new cells resembling the mother-cell. Under certain conditions of rest, etc., the Amœba assumes a globular form, and becomes invested with a cellmembrane or cyst, as is shown in the accompanying engraving.*

*The engravings Nos. 4, 5, and 6 are taken from Haeckel's original work, the Professor having most

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THE REGNUM PROTISTICUM, OR

A is the Amoeba, a simple spherical cell, consisting of protoplasm (c), containing

a nucleus (b), and a nucleolus (a), the whole organism being enclosed in a cellmembrane (d). B. The Amoeba has ruptured and escaped from the cyst. C. The nucleus has separated into two nuclei, and the Amoeba itself is constricted by a median furrow. D. The division is complete, and two independent cells are formed, each with its proper nucleus. (Da Db). The white corpuscles of the blood of man and of animals, says Haeckel, cannot be distinguished from these Amœbæ.

The study of this elementary form has evidently great attraction for the German Professor who says that, after the Monera, the Amœbæ are the most important of all

courteously permitted me to reproduce them from blocks supplied to me by his publisher at Berlin.

FIG. V.-THE SECOND GROUP OF THE PROTISTIC KINGDOM.

The above engraving shows the mode of reproduction in a monocellular organism, by segmentation or self-division, as exemplified in the Amoeboida or Protoplasta.

KINGDOM OF PRIMITIVE FORMS.

37

organisms in a biological, and especially in a genealogical, point of view.

The third group of this kingdom of Primitive Forms is that of the Flagellata, which are organisms consisting of simple cells, living in fresh or in salt water.

They are characterised by a flagelliform appendage, such as is represented in figure VI., which serves for the purpose of