G4 DUBLIN UNIVERSITY 



He commenced by stating the rare occurrence among the Algae of 

 any variety of cellular tissue different from ordinary parenchyma. "With 

 the exception of the web of anastomosing fibrils, which exists within 

 the cells of the genus Caulerpa, and a somewhat similar, but less deve- 

 loped, fibrous emanation from the inner face of the cell-wall in Dictyo- 

 sphaeria, he was not acquainted with any other instances in which fibres 

 were developed within the cells of the Algae. The Alga now exhibited 

 to the Meeting was named Blodgettia confervoides, and he had referred it 

 to the family Valoniaceae. It externally resembled a branching Con- 

 ferva or Cladophora so closely, that, before he had minutely examined it, 

 he had actually distributed specimens to some of his correspondents, 

 under the name of Cladophora ccespitosa. The structure of the cells of 

 which it is composed, however, forbids its being associated with Clado- 

 phora, in which genus the frond consists of a branching string of mem- 

 branous-walled cells, of the ordinary structure found among the Algae. 

 The frond in Blodgettia equally consists of a branching string of cells ; 

 but the structure of their cell- wall is highly compound. It is easy, by 

 making transverse and longitudinal sections of the cell, to separate por- 

 tions of the cell- wall, which, by a little careful manipulation, may then 

 be shown to consist of several separate membranes developed one inside 

 the other. The outer coats of the cell, to the number of two or more, 

 may be separated as perfectly transparent, homogeneous films ; but the 

 innermost coat, which encloses the grumous endochrome is of thicker 

 substance than the external films, and is traversed by numerous longi- 

 tudinal fibrils, connected together in an irregular manner by anastomos- 

 ing cross- veinlets. The membrane thus appears marked with a fibrous 

 network, with oblong meshes, which are somewhat pointed at each ex- 

 tremity, and are longer or shorter, but averaging a length of four to five 

 times their diameter. Besides the anastomosing veinlets, there are others 

 which may be said to be free, — in the sense that the veinlets in a fern- 

 frond are so called, — as they terminate in the centre of the areole formed 

 by the anastomosis. To these free veinlets are attached moniliform 

 strings of spherical cells, which Dr. Harvey was disposed to regard as 

 spores. If such be their nature, they are probably retained iu the cell 

 until the decay of its walls. For a figure of this structure Dr. Harvey 

 referred to the 45th Plate of "Ner. Bor. Amer.," Fig. C, which was 

 shown to the Members present, and at the same time sections of the 

 netted membrane were examined with one of the microscopes on the 

 table. 



