2 Introduction to Animal Morphology. 



this body (Protoplasm or Bioplasm), white blood 

 corpuscles, the yelk spheres of eggs, the contents of all 

 growing cells, are examples. This substance shows 

 three forms of motion under different conditions : — ist. 

 When diluted with water, internal currents indicated 

 by the circulation of enclosed particles, the outline of 

 the mass being unaltered ; a more definite motion than 

 the Brownian cyclosis of non-living fluids, and con- 

 nected with chemical change. 2nd. Motion attended 

 with change of form, irregular contractions of the whole 

 mass, with temporary protrusions at one part (called 

 pseudopodia), and recessions elsewhere; thus locomotion 

 can take place.* This form of motion maybe changed 

 into the first by dilution, or the former into it by the 

 action of a weak (2^) solution of NaCl. 3rd. Ciliary 

 motion,t the protoplasm mass having on its surface 

 constant hair-like processes of its own substance^ 

 (cilia), rapidly vibrating to and fro, either from within 

 (as in spermatozoa) or from the outer layer of the mass. 

 Long whip-like cilia are called Jlagella^ if sub-rigid, 



* Thus Amcebse wander in the waters wherein they live, and white 

 blood corpuscles through the tissues of the bodies of higher animals, as 

 Waller, Recklinghausen, and Cohnheim have described. Such cells are 

 probably used as tissue-pabulum, as young noticed in connective tissue, 

 Biesiadecki and Pagenstecher in epithelium, and Strieker, &c., in deve- 

 loping embryos. 



t Gegenbaur regards cihary motion as different from protoplasmic. 



:J: Flagella have been seen changing into pseudopodia in Protomyxa 

 (Haeckel) and in Myxomycetes {De Bary). The converse, or cilia changing 

 into pseudopodia, occurs in Magosphaera {HaeckeT). Ciha are never out- 

 growths from a cell-wall, nor vacuolated nor granular. The granules 

 observed by Alexafider Stuart in Opisthobranchiata have not been con- 

 firmed by others. Stuart has also described fine lines passing from the 

 cilia to the cell nucleus, which by contraction moved the nucleus ! Pro- 

 bably these are of the nature of the longitudinal striae found by Eherth in 

 cells of ciliated epithelium. 



