OP ARTS AND SCIENCES. 115 



two or three of them whorled. He says they seemed to be formed by 

 an outgrowth from the lonsr cell. 



A paper appeared in 1882* by Dr. G. Berthold, in which he inci- 

 dentally gives a general description of structure and method of growth 

 in Champia parvula, Lomentaria kaliformis, Chylochladia reflexa, 

 Harv., and Ch. mediterranea, J. Ag. 



He gives a diagram of the tip of Champia parvula, and points out 

 that there is not a single apical cell, but a group of them, and accord- 

 ing to him they are arranged in a very definite way. At the apex 

 four of these cells form a cross, only two of them however meeting 

 in the middle. From the outer side of each of these cells is given 

 off a row of cells derived from this apical cell, and very gradually 

 increasing: in width. In the angles of the cross thus formed are 

 four other apical cells which give rise to similar rows ; and then the 

 remaining space is filled by a third series, usually of eight apical cells 

 and their progeny, making in all sixteen rows of cells each headed by 

 an apical cell. The cells of these rows are flattened at right angles 

 to the axis, and give rise to other cells by oblique division. According 

 to Berthold, these second cells may divide again in like manner, thus 

 forming the peripheral covering cells, while the first do not divide, 

 but become much enlarged. 



Berthold was the first to point out that the longitudinal filaments of 

 the adult frond correspond exactly in number and position to the api- 

 cal cells in Champia. 



In 1886, in a paper by N. Wille,t we again come across a study of 

 Lomentaria kaliformis. He finds in this species a conical apical cell, 

 which, dividing in several directions, sometimes parallel to its base, 

 sometimes at right angles to the surface of the thallus, gives rise to 

 other cells. These cells again divide into an inner small cell and an 

 outer large one, the outer one dividing again into two. The outer 

 cells are the only ones in which division continues. The inner ones 

 do not divide, but, elongating, produce the longitudinal filaments. 

 Wille hints that the diaphragms are derived from these filaments, but 

 he does not tell how. 



Summing this up, we see that Niigeli thinks there is a single api- 

 cal cell in Lomentaria kaliformis ; and Wille describes one very clearly 



* Berthold, Dr. G., Beitriige zur Morphologie und Physiologie der Meersal- 

 gen. Jahrbucher f. wiss. Botanik, Bd. XIII., 1882, p. 686. 



+ Wille, N., Beitrage zur Entwickelungsgeschichte der physiol. Gewebesys- 

 teme bei einigen Algengattungen. Bot. Centralblatt, 1886, VII., Qr. XXVI. 

 p. 86. . 



