22 2 THE AMERICAN NATURALIST. [Vol. XXXIX. 



sphere is connected with its neighbors generally by six strands 

 of protoplasm, only a few of which could possibly be left by the 

 successive cell divisions. The majority must have developed as 

 outgrowths from the plasma membrane of the cell. 



Numerous instances of cytoplasmic connections among the 

 fungi have been reported by many authors. A general review 

 of the subject is presented by Kienitz-Gerloff (: 02) and in a 

 lengthy paper of Meyer (:02). The protoplasmic connections 

 fall into two groups : (i) those that remain in the center of the 

 wall after a cell division, and (2) the kteral unions and clamp 

 connections which are developed entirely independently of cell 

 division. Connections of the first type, i. e., those between 

 daughter cells, appear to be very general in the Ascomycetes 

 and Basidiomycetes and are essentially similar to the strands 

 between cells of the Rhodophyceae. They are especially well 

 illustrated in members of the Laboulbeniaceae (Thaxter, '96 ; 

 see Fig. 16, f). In the second group are the clamp connections 

 (Fig. 16, g), characteristic structures of the tissues of fleshy 

 forms of the Basidiomycetes, and the lateral unions between 

 cells of closely entangled hyphse which are well known in a 

 number of forms and have been followed in cultures from germi- 

 nating spores. It is probable that the fusions between sporidia 

 in the smuts are also of this class, although De Bary and others 

 have attached sexual significance to the phenomenon (especially 

 as illustrated by Tilletia). Harper ('99a) has studied the fusions 

 of the conidia of Ustilago and finds that they concern the cyto- 

 plasm alone. However, Federley (:03-:04) has reported a 

 nuclear fusion in one species (Ustilago tragopogonis pratensis 

 Pers.) but states that others agree with Harper's account. 

 Extensive experiments of Brefeld have shown that the fusions 

 of sporidia depend largely upon the character of the nutrient 

 media and are less likely to occur when the conditions are favor- 

 able. He considers the fusions as purely vegetative processes 

 comparable to the unions of germ tubes of spores {e. g., Nec- 

 tria, Sclerotinia, Rhyparomyces, etc.) into a common mycelium 

 and to the connections between hyphae of Basidiomycetes. 

 Recent studies of Blackman (: 04 a) indicate also that sexual 

 processes should not be expected at this period in the life his- 



