On the Morphology and Physiology of the Cell. 213 



lulose coat in many algse, e.g., Enteromorjpha (fig. 2), is also 

 very evident. 



14. Passing to the consideration of the modes of cell divi- 

 sion, I shall not at present venture upon any bibliographical 

 account, but content myself for the present by briefly refer- 

 ring to such contributions as I have already published. * 

 The first relates to the process of cell multiplication by means 

 of interlaminar gemmation (fig. 2). The second describes the 

 origin of the brown corpuscles of Echinus by a process (highly 

 suggestive of comparative researches) which appears to be a 

 variety of that of free cell formation, from certain of the pig- 

 ment granules which occur in masses in certain portions of 

 the blood vessels and water-vascular system (fig. 1). Finally, 

 I have figured specimens of Chlamydomyxa, which at least 

 closely simulate, if they do not, as is much more probable, 

 absolutely represent all tlie main modes of cell multiplication 

 — transverse division, gemmation, free cell formation, and 

 rejuvenescence — with which we are acquainted, and which 

 at any rate assist us in imagining how these processes have 

 arisen (see fig. 3). 



Explanation of Plate. 



Fig. 1. Endogenous (?) development of brown amoeboid corpuscles of sea 

 urchin : t a, three of the yellow granule-masses from the ambulacral pouch, 

 with one free brown corpuscle (at left hand upper corner) ; h, c, d, similar 

 granule -masses from intestinal blood vessel, the two latter showing one or 

 two of their constituent spherical bodies enlarged and darkened in colour ; 

 e, a granule-mass with dark coloured body, now of irregular form ; /, the 

 same under j)ressure ; at g, completely expressed (bom, in fact) as a brown 

 amoiboid corpuscle ; h, another brown corpuscle, more highly magnified, and 

 showing dark coloured granules in colourless protoplasm ; i, the same corpuscle 

 killed and decolorised ; j, a corpuscle crushed ; I; proliferation and escape 

 of small spherical yellow bodies (nucleoli?) from nuclei of epithelial cells of 

 ambulacral pouches, by union or division of which the yellow granule-masses 

 seen in figs, a, h, appear to originate. 



Fig. 2. Cell-multiplication by interlaminar gemmation in Enteromorpha :% 

 a, a filament with laminated structure of cellulose brought out by weak 



* Op. cit. 



+ S. 1, fluide Perivisceral d. Oursins, Arch. d. Zool., Exp., vol. viii., 

 pi. 38. 



X On the Phenomena of Variegation, etc., in Enteromorpha (Trans. Roy. 

 Soc. Edin., vol. xxix., pi. 12). 



