inO AET. 12. — K. YENDO. 



able to find a case in which a frond of the foliose type was 

 growing on any alga other than either of the two types under 

 consideration. Repeated examinations have been made on sections 

 through the adjoining points of the two forms. In every 

 case it was revealed nothing except that the hypheal cells of 

 the segment of the filiform frond passed into the stem of the 

 foliose one without any indication that the two different forms 

 belonged to separate plants. And in the case in which the 

 abnormal foliose branches were found on a frond of the foliose 

 type, the section through the point of insertion showed only 

 a slight disturbance in the cortical tissue at that point, and 

 nothing else. The two types will be regarded as the two forms 

 of a dimorphic plant, though positive proof for doing so is 

 lacking. The determination is, therefore, a provisional one to be 

 held until it has been proved that the two types belong to 

 different species. 



The fiicts that the abnormal foliose branches, whether they 

 be on a frond of the foliose type or of the filiform type, are 

 always accompanied by the parasitic organism infesting the 

 princij^al frond, and that they are found fasciculately at the 

 same point, remind us of the witches' broom of a flowering plant. 

 The malformations of Ascophylhim and Cystoseira have been 

 reported by Baeton^^ and Valliante.-^ But in these cases no 

 disturbance in the ramification of a frond was observed. We 

 are familiar with the fronds of Fusus evanescens, which have 

 numerous stunted branches growing at an internodal jioint or on 



1) Barton : Malformation of iVscophj-lliim and Desniarestin, in Mukray, Pliyc. Mem. 



PI. ir. p. 21. 



2j Valliante: Le Cystoseirae del Golfo di Napoli. Fauna n. Flora de.s Gofes von 

 Neapel. 7. 



