64 ORGANIC EVOLUTION — THE FACTORS 



In Mr. Spencer's view then, the multicellular organ- 

 ism is not a compound being, a being compounded of 

 adherent unicellular organisms, but a simple being, of 

 which the cells are parts, but not absolutely essential 

 parts, since parts of the organism may arise independ- 

 ently of cells. His work was written some years ago, 

 and he does not give his authorities. I have searched 

 every recent work I could lay hands upon, and have 

 found no warrant for his statement that fibrous tissue 

 ever arises independently of cells. Dr. Klein says — 



"Fibrous connectivetissue is developed from embryonal 

 connective tissue cells, i. e. from spindle-shaped or 

 branched nucleated protoplasmic cells of the mesoblast. 

 The former are met with isolated or in bundles, as in 

 the umbilical cord or embryonal tendon. The latter 

 form a network as in the fcBtal skin and mucous 

 membrane. In both instances the protoplasm of the 

 embryonal connective tissue cells becomes gradually 

 transformed into a bundle of elementary fibrils, with a 

 granular-looking interstitial substance. The nucleus of 

 the original cell finally disappears. A second mode of 

 the formation of connective tissue is this : the embryonal 

 connective tissue cell, while growing in substance, pro- 

 duces the fibrous tissue at the expense of its peripheral 

 part. A remnant of the protoplasm persists round the 

 nucleus. 



"The same modes of formation of connective tissue 

 may be also observed in the adult, under normal and 

 pathological conditions." — Elements of Histology, p. 42. 



As regards rhizopods again, I can find no warrant 

 for the positive statement that they are not cellular. 

 Some of them are apparently not cellular, but we have 

 good reason for supposing that they really are so, 

 though with the imperfect means of observation at our 

 disposal we are unable to distinguish the cells. 



In Claus's Zoology, translated and edited by Adam 

 Sedgwick, I find — " Nuclei are also usually present in 



