372 PEOP. TH. ^Y. ENGELMANN. 



cetes/ by Haeckel in Protomyxa/ in the ciliated epithelium of 

 calcareous Sporiges,^ the segmentation spheres of Siphonophora/ 

 and by Clark among Flagellata.^ 



Protoplasmic movement, properly so called, is to be distin- 

 guished from the changes of external form and internal 

 arrangement of the protoplasm which occur during growth and 

 reparation, segmentation, fertilization, &c., of cells, principally 

 by its greater rapidity and its non-relation to all growth and 

 reproduction. But here, again, there is no sharp limit, as 

 shown, for instance, in the phenomena of fission among Pro- 

 tamoebse. Amoebae, and colourless blood-corpuscles, and the 

 increasing internal movements preparatory to spore formation, 

 which occur in the cells of many Algse and Fungi.^ 



Historical. — The oldest description of a protoplasmic 

 movement which I have been able to come across is by Rosel 

 von E-osenhof.''' 



The small "Proteus" which this excellent observer described 

 and figured in the year 1755 was a large freshwater Amoeba. 

 Rosel distinguished between a richly granular interior and a 

 hyaline peripheral portion (" ein zartes ausseres Hautlein), 

 figured the unceasing changes of shape, the assumption of the 

 spherical form in consequence of mechanical excitation, and 

 the phenomenon of fission ; this latter, by-the-bye, the first 

 direct observation of a cell-division. Following close upon 

 this, twenty years later, comes Bonaventura Corti's^ celebrated 



1 ' Zeitschr, f. wissenscb, Zool.,' x, p. 153, 1860. 



2 ' Jeuaische Zlschr.,' iv, p. 87, 1868. 



3 Ibid, V, p. 543, 1870. 



^ ' Eutwickelungsgeschiclite d. Siplionoph.,' pi. vi, fig. 36 ; pi. xiv, fig. 93, 

 Utrecht, 1869. 



5 ' Mem. Bost. Soc. Nat. Hist.,' 1867, pis. ix and x. 



® Concerning the latter phenomena cf. W. Hofmeister, 'Die Lehre von der 

 Pflanzenzelle,' p. 45, &c., Leipzig, 1867. 



'^ Uosel von Rosenhof, ' Der monatlich herausgegebenen Insectenbelusti- 

 gungen,' dritter Tlieil, pp. 621—623, pi. ci, figs, a— w., Niirnberg, 1755. The 

 " Proteus " described shortly previous to this by Baker, is Trachelocerca 

 olor, a holotrichous Infusorian. 



^ B. Corti, ' Osservazio'ni microsc. sulla Tremella e suUa circolazione del 

 fluido in una pianta acquajola,' Lucca, 1774. 



