from the Cell-contents of the Characese. 125 



" green disks ;" as they are situated when seen to undergo rota- 

 tory motion. 



Vig. 18. " Globular vesicle " of large Nitella, containing agariciform " ir- 

 regular body." 18'. Ditto of small Nitella, containing in addition 

 to its nucleus an irregular body imbedded in its granuliferous 

 mucus ; as it is situated when seen to undergo partial rotatory 

 motion. 



Fig. 19. Portion of internode of Nitella, showing the breaking up of the 

 green layer preparatory to grouping of the green disks. 



Fig. 20. Ditto, with green disks grouped or enclosed in the " globular 

 vesicles." 



Fig. 21. Groups which have assumed a spherical form : (a) globular vesicle 

 or so-called " gonidial cell " stiffened and clarified, yet capable of 

 projecting ambulatory processes (see fig. 23 a) ; (b) secondary 

 coat circumscribing granuliferous mucus, green disk, &c. 



Fig. 22. " Globular vesicle " showing internal granuliferous mucus circum- 

 scribed by secondary coat, mass of green disks, and " circular 

 disk." 



This form is often seen without the mucus in a perished, half- 

 developed state, when the " circular disk " is always particularly 

 evident ; thus with the other elements of the cell at once indicating 

 its identity with the " globular vesicle " and rhizopodous nature. 



Fig. 23. " Globular vesicle " showing secondary coat, granuliferous mucus, 

 and mass of green disks all now separated ; (a, a) stifi'ened ambu- 

 latoiy processes. 



Fig. 24. Ditto, with granuliferous mucus presenting a mulberry form of 

 segmentation. Cell about l-300th of an inch in diameter. 



Fig. 25. Ditto, lateral view. 



Fig. 26. Ditto, after separation of the segments into monads, and disap- 

 pearance of the secondary coat. 



Fig. 27. Ditto, bursting and giving exit to the monads, green disks, &c., 

 and other efifete matter contracted into a small brown nucleus. 



Fig. 28. Small " globular vesicle " with " irregular body " in the position 

 of the nucleus, developing one monad only. Cell or vesicle 

 l-2150th of an inch; monad l-4300th of an inch in diameter. 



Figs. 29, 30, 31. Monads of the globular vesicles or cells assuming dif- 

 ferent forms. All about 1 -4800th of an inch in diameter when 

 globular. 



Figs. 32, 33, 34. The same after a few days' growth; now about 1-2 150th 

 of an inch in diameter, assuming the forms of Amoeba and Actin- 

 ophrys ; with contracting vesicle. 



Fig. 35. Vertical section of a young plant of Chara verticillata, with nucule 

 still attached, (a) nucule : (b) external cellular coat ; (c) middle 

 or laminated black coat ; (d) internal delicate coat ; (e) circlet of 

 roots springing from cells of first node ; (/) second position of 

 cytoblast, viz. at the termination of the granuliferous mucus which 

 fills the extremity of the root ; (g) third position of the cytoblast, 

 viz. when attached to the side of the root at some distance from 

 the granuliferous mucus of the extremity ; {h) circlet of roots 

 arising from the cytoblast so situated. The small figures, 1 to 6, 

 indicate cells of the stem in successive stages of development; 

 showing that the formation of the " mucus-layer " is preceded by 

 the presence of a mass of hyaline, spherical vesicles of difi'erent 

 sizes, which at first fill the young cell. 



Fig. 36. Last three cells (viz. 4, 5, 6) of fig. 35, more magnified. 



Fig. 37. One of the new root-buds of (A), fig. 35, magnified, to show that 



