84 Dr. Willshire's Contributions to Structural Botany. 



having constrictions at distant intervals, and which appear to 

 me to be merely forms of very elongated, flattened, metamor- 

 phosed, confervoid cells. In the flat fronds it is rather diffi- 

 cult to discern the walls of the cells without attentive obser- 

 vation; but with care, and a due regard being paid to the 

 transmission of light from the mirror of the microscope, an 

 eye accustomed to the appearances vegetable structures pre- 

 sent will soon detect them. The termination of the frond is 

 rounded, or more or less sharply conical, the length variable 

 from a line to nearly half an inch, the breadth depending upon 

 the number of serial cells primarily developed, and the whole 

 plant often twisted, waved or curled. 



In the second volume of Sir J. W. Hooker^s ' Flora ' our pre- 

 sent plant is arranged under the genus Ulva, with the remark 

 appended, that " although arranged by Captain Carmichael 

 among the Bangice, it is but justice to his memory to state 

 that he remarked in a note that this plant and Bangia velu- 

 tina of Lyngbye were more nearly allied to the Ulvce than to 

 the gelatinous Bangia of the second division." 



Mr. Harvey, in his late work, also arranges it in the same 

 genus [Ulva). To me it does not appear to have its natural 

 location in this genus ; it is true that the plant is wanting in 

 some of the characteristics of the satisfactorily determined 

 BangicB, as stated by Captain Carmichael, and also that the 

 flattened forms of it do simulate to a considerable extent the 

 characters of the genus Ulva. I look upon it as certainly 

 confervoid in its earliest state, and always so in certain of its 

 perfect and adult conditions ; but that it also becomes meta- 

 morphosed into a form which closely approximates to that of 

 the family Ulvacece. The genus Bangia has already been 

 supposed a group of the Confervce by some botanists, and 

 which has certainly a connexion with our present plant, but 

 yet not sufficient to admit of its reception. It appears, under 

 all considerations, by no means unwarrantable that this plant 

 shall form the type of a new family intermediate between 

 Confervce and Vlvacece, a family osculant of these two, con- 

 necting the family Confervce to Ulvacece by the genus Bangia 

 however rather than by that of Ulva. 



2. — Two or three years ago it was stated by Dutrochet, 

 that in the nodi of Viscum album no true woody matter 

 existed ; that the vascular connexion of the internodial spaces 

 was therefore broken up, or was only maintained by a layer 

 of cellular tissue or pith : this doctrine was admitted, and 

 Viscum was supposed to form another illustration of what 

 have been called articulated stems. Some time after Decaisne 

 published a small work on the woody structure of this plant, 

 in which he contradicted the statement of Dutrochet, and 



