ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 683 



and the strongest alkalies, as well as the disintegrating action of a 

 solution of bleaching powder. Within this ring the arrangements 

 are not the same in all cases, but for the most part they conform to 

 one of four types. 



1. In the first type the ring surrounds a comparatively wide and 

 open pore, through which the protoplasm is continuous in a single 

 thread. This type is not very common, but isolated cases are to be 

 met with here and there. 



2. In the second type a delicate diaphragm stretches across the 

 space inclosed by the riug, and through this the protoplasm is con- 

 tinuous, as through a sieve-plate, by a number of delicate threads. 

 This is perhaps the commonest form of continuity, and bears the 

 closest possible resemblance to that met with in the sieve-tubes of 

 higher plants. 



3. The third type agrees with the second, except that continuity is 

 effected by a thin and delicate ribbon of protoplasm which passes 

 through a narrow slit in the diaphragm. This form is not abundant, 

 and appears to be intermediate between the second and the fourth. 



4. In the fourth type the diaphragm is complete and impervious, 

 except at the centre, where there is an extremely minute pore, through 

 which a single delicate strand of protoplasm maintains the con- 

 tinuity. 



The delicate diaphragm met vp'ith at the ends of the cells, like 

 the annular thickening which incloses it, does not swell up under 

 the action of reagents, nor does it stain like the rest of the walls. 



In Fucus vesiculosus and serratus the same phenomena of con- 

 tinuity were observed, both in the layers of cortical cells and in the 

 fibres which arise from them and curve inwards to interlace with the 

 central filaments. 



Fertilization of Cryptonemiaceae.* — Dr. G. Berthold publishes a 

 monograph of the species of this family of Florideae found in the 

 Bay of Naples, belonging to the genera Halymenia, Grateloupia, 

 Cryptonetnia, Schizymenia, Sebdenia, Halarachnion, Nemastoma, Gym~ 

 noph/cea, Calosiphonia, and Budresnaya. These are classified by the 

 author under four tribes : — Halymenieaj, including Halymenia, 

 Cryptonemia, Grateloupia, and perhaps Schizymenia ; Nemastomcse, 

 including Dudresnaya, Calosiphonia, Nemastoma, and Gymnophlcea ; 

 while Sebdenia and Halarachnion each constitutes a tribe by itself. 



The vegetative structure presents nothing very remarkable. In 

 most forms there are found at the apex several apical colls, from which, 

 lying side by side, the thallus is constructed. Dudresnaya and 

 Calosiphonia differ from the remaining genera in presenting only a 

 single apical cell. In none of tlie Cryptonemiacea) are tetraspores 

 found on the same individual as the sexual organs. 



Tlie mode of fertilization presents in all the genera the same 

 essential features as that already known in Dudresnaya and Polyides. 

 The lower portion of the impregnated trichogyno is separated off by 



• Bortholf], G., ' Cryptonemiaceen. P'auna u. Flora dos Golfes v. Neapel. 

 Monog. xii., 27 pp. (8 pla.;. 4to, Leipzig, 1884. 



