To face p. 176.) , 
DESCRIPTION OF PLATES. 
Pirate I. 
Fig. 1.—A. Heteromita rostrata (Kent). 
1—B. Monas Dallingert (Kent). 
2—C, D. H. vostrata undergoing fission. This was seen in earlier studies to 
begin in the body, and apparently afterwards (as in c, d) to extend to the 
nucleus. 
3,—Almost complete division of the body and the nucleus of the same; but a 
fibrous connection exists between the two parts of the nucleus. 
4—Total severance of the nucleus, and the division of the body and the 
flagella is almost complete. 
» 3-—4 H. vostrata produced by fission. 
6—The final product of a long series of fissipartitions undergoing the change 
preceding sexual fusion. 
Figs. 7, 8.— The process of fission in this special form. 
Fig 9.—The initiation of fusion in an ordinary form with one of the above. 
Prate Il 
Fig. 10 —Early result of fusion of two of these forms; the nucleus has blended, and 
exhibits a radial condition. 
11.—A sac resulting from the complete genetic fusion of the two individuals. 
12. —The ripe sac bursting and emitting minute semi-opaque spores. 
13.—A study with great magnification of the nucleus separately. This repre- 
sents the nucleus before any evidence of change is discoverable. 
14 —The first evidence—seen only in the nucleus—of approaching fission in the 
organism; beaded threads appear throughout the plasm; and a line 
shows itself incident with the long diameter of the organism. 
15.—The fission begins in the body at a, but has been preceded bya con- 
densation of the beaded structure to the right and left of the division- 
line 
Figs. 16, 17, 18.—The nucleus seen in process of fission, almost divided (as seen in 
Fig. 3, pl. i.) and immediately after division. 
Fig. 19.—Nucleus after division in the exceptional form shown in Fig 8, k, pl. i. 
,, 20—Condition of the nuclei in the fused forms 
» 21.—g,h, i. Growing spores. 
», 22—j. The spore grown to the size of a nucleus, a pause takes place in actual 
enlargement by growth, and internal development of the beaded structure 
arises as at k. 
23 —After the internal development of the nucleus the body begins to great 
apparently from the nucleus, and the flagella, /, m, are pushed out; after 
this, growth to the normal size is rapid 
Natura Science, Vol. Il. 





Naturat Science, Vol. II. 





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