318 THE MICROSCOPE. 



in an early stage of development." The Characeoe are all 

 aquatic plants of filamentous structure. Some authors 

 have divided the species into two genera, Nitella (simple 

 tubes) and Char a (cortical tubes). The circulation in 

 the ordinary tubes or cells consists in the movement 

 of the gelatinous protoplasmic sac, seen, as one mass, slowly 

 passing up one side, across the ends, and down the 

 opposite side, not perpendicularly, but in an oblique or 

 spiral course, as indicated in the figure. The CJiaraccce 

 multiply by gemmae, produced at the articulations of 

 their stems. 



Mr. 11. J. Carter, in a paper of great interest, published 

 January, 1857, on the "Development of the Root-cell and 

 its Nucleus, in Chara Verticillata," describes a structureless 

 cell-wall, and a protoplasm composed of many organs. 

 " This," he says, " is surrounded by a cell, the ' proto- 

 plasmic sac,' which is divided into a fixed and rotatory 

 portion ; these again respectively enclose the nucleus 

 ' granules,' and axial fluid ; while small portions of irre- 

 gular shaped granular bodies are common to both. If 

 we take the simple root- cell about the eighteenth hour 

 after germination, when it will be about half-an-inch long, 

 and 1 -600th of an inch broad, and place it in water between 

 two slips of glass for microscopic observation, under a 

 magnifying power of about four hundred diameters, we 

 shall find, if the circulation be active and the cell -wall 

 strong and healthy, that the nucleus, which is globular, 

 gradually becomes somewhat flattened, having several 

 hyaline vacuoles of different sizes ; the change goes on 

 gradually until it appears of more elongated form, growing 

 fainter on its outline, and then entirely disappears, leaving 

 a white space corresponding to its capsule or cell-wall, 

 with a faint remnant of some structure on the centre. 

 Subsequently, this space becomes filled up with the fixed 

 protoplasm, and after an hour or two the nucleus re- 

 appears a little behind its former situation, but now 

 reduced in size, and with its nucleolus double, instead of 

 single as before ; each nucleolus being about one-fourth 

 part as large as the old nucleolus, and hardly perceptible. 

 Meanwhile a faint septum is seen obliquely extending 

 across the fixed protoplasm, a little beyond the nucleus ; 



