224 TUFTS COLLEGE STUDIES, VOL. II, No. 3 



can usually be recognized as such. The chief difficulty lies in 

 the fact that different organs may be distributed over two or 

 three distinct classes of filaments, and it is by no means easy to 

 get all in the same collecting. Add to this the fact that differ- 

 ent species frequently grow together, so that it is rather the ex- 

 ception to make a collection all of one species, and it will be 

 seen that it is only too easy to overlook one of the forms of the 

 species under consideration, or to mistake for it a filament of 

 another species. 



The peculiarities of the species of Oedogonium require a num- 

 ber of special names to be used in the descriptions, and they 

 may be summarized as follows : the antheridia and oogonia may 

 occur on the same filament (monoecious species) or on separate fila- 

 ments (dioecious) ; in the latter case the male filaments may be 

 nearly similar to the female (macrandrous species) or very much 

 smaller (nannandrous). In the latter case the male filaments 

 (nannandres, dwarf males) are minute plants of a few cells each, 

 epiphytic on the female filament, usually on the oogonium or 

 on the cell below it (suffultory cell). These dwarf males are 

 produced by the germination of special spores (androspores) 

 produced in androsporangia ; the androsporangia are short cells, 

 usually narrower than the vegetative cells of the filaments in 

 which they occur ; they are either single or two or more in a 

 series ; they occur in the same filament as the oogonia (gynan- 

 drosporous species) or in separate filaments (idioandrosporous) ; 

 when the former they may be directly above the oogonium (epigy- 

 nous) or a short distance above the oogonium (subepigynous), di- 

 rectly below the oogonium (hypogynous), or a short distance 

 below (subhypogynous). When occurring without any reference 

 to the oogonium they are said to be scattered. The dwarf males 

 may be unicellular, the spermatozoids being produced in the 

 single cell, or pluricellular ; in the latter case the antheridium 

 may be produced merely by a partition forming in the originally 

 unicellular male (antheridium interior) ; or in a cell or in the 

 upper of two or more cells formed at the summit of the male by 

 the typical Oedogonium cell division (antheridium exterior) ; in 

 this case the'part below the antheridium is known as the stipe, 

 and may'be one to several celled. An antheridium may pro- 



