ZOOLOGY AND BOTANY, MICEOSCOPY, ETC. 263 



The fact that the colls themselves increase in size during the 

 formation of mucilage, necessitates the hypothesis that intussuscep- 

 tion takes an active part in the formation of all those layers vphich 

 are formed before the completion of the growth of the cells. If 

 growth took place by apposition only, the layers would be formed 

 only after the cells had obtained their full size. 



The walls of the mucilage-tubes do not assume a condition 

 capable of swelling during their development, but retain their struc- 

 ture to the end. The death of the thallus causes the tubes to open 

 in succession and discharge their contents. The disorganization of 

 the mucilage-cells in the end of the thallus takes place in the 

 same way. 



Nothing can be said with certainty with regard to the physio- 

 logical function of the mucilage-organs of the Marchantiacese, but it 

 is probably connected with their great power of swelling, owing to 

 the capacity of their contents for absorbing water. 



Characeae. 



Characeae of the Argentine Republic* — C. Spegazzini describes 

 six species of Nitella, with four forms, one of Lamprothamnus, and 

 three of Chara, with two forms. The species of Lamprothamnus is 

 new, and is thus described : — L. Montevidensis Speg. Maximus, crassus, 

 capitate ramosus, ecorticatus, monoicus. Antheridia globoso-polygona, 

 rufo-fusca v. rufo-rubra (0 • 20-0 • 22 mm. diam.) ; sporangia ad basin 

 antheridiorum enata, infera, globosa (0-30-0 "35 mm. diam,), rubes- 

 centia, subinconspicue 5-7 gyrata, apice coronula mammiforme, obtusa 

 breviusculaque ornata. Near Montevideo. 



American Species of Tolypella.t — The two families into which 

 the Characeae may be divided are distinguished by the structure of 

 the corona of the sporangium (archegonium), which consists in the 

 Charese of five, in the Nitellese of ten cells ; in some species of the 

 latter family it is evanescent. The Nitelleae again may be divided 

 into two genera, distinguished chiefly by the position of the antheri- 

 dium, which in Nitella is apical, on the primary ray of the leaf, the 

 archegonia being lateral on the node below the antheridium ; and the 

 leaves having but one leaf-bearing node. In Tohjpella the antheridia 

 are one or several, lateral on the nodes of the leaf and leaflet ; the 

 leaves have from one to three nodes bearing leaflets. 



T. F. Allen gives a full account of the American species of 

 Tolypella, and proposes the following general classification of the 

 twelve known species of the genus, of which four are now described 

 for the first time : — 



I. Obtusifolia. — Corona evanescent ; sterile leaves undivided. 



A. Ultimate cell of the primary ray of the leaf longer than the 



other cells. 1 sp. : — T. longicoma A. Br. 



B. Ultimate cell not longer. 4 sp. : — T. nidifica Leonh. ; T. 



Normaniana Ndst. ; T. glomerata Leonh. ; T. comosa Allen. 



• Ann. Soc. Cientif. Argentina, xv. (1883) pp. 218-31. See Bot. Centralbl 

 xvi. (1883) p. 257. 



t Bull. Torrey Bot. Club, x. (1883) pp. 109-17 (6 pis.). 



