Tilden: PILINIA AND STIGEOCLONIUM. 615 



thallus. By including Pilinia as a stage of Stigeoclonium, 

 each of these three types of reduction has its representative 

 as shown by PL XXXII, fig. 6, 5, in the case of the first and 

 third examples. 



Huber quotes from Berthold (I). ' 'Many species of Stigeo- 

 clonium form, in germinating, a creeping "rhizome," more or 

 less branched, upon which develop the upright filaments, 

 which branch in their turn and constitute the point of de- 

 parture of a series of remarkable reductions". This author 

 further remarks "It is not rare, that in the first stages of 

 development of the epiphytic forms of the genus Stigeoclonium, 

 those having the creeping thallus strongly developed, furnish 

 (sometimes side by side with the ordinary raised branches) 

 the upright branches entirely transformed into pericellular 

 bristles." One infers from this that the phenomenon has not 

 heretofore been observed in species of Stigeoclonium which 

 were not epiphytic. 



Berthold, as quoted by Huber and Moebius (I), affirms 

 that the cells of the bristle in Stigeoclonium are 10-15 times 

 longer thau those of the vegetative tract. The Belief onte 

 species does not confirm this statement. Some of the fila- 

 mentary cells are 72 mic. and more in length, while no bristle 

 cell has been observed more than three times this length. It 

 should be noted, however, that the bristles themselves are 

 exceedingly long. 



Berthold (Moebius I. 84) was also able to develop bristles in 

 great abundance after four weeks' culture in material which 

 at the time of its collection (early in the year) was entirely 

 without them. This corresponds with the behavior of the 

 Bellefonte plant which has been the same in every case. 



An increase in the number of pyrenoids in the upper cells of 

 the filaments and branches indicates that the time for the 

 formation of megazoospores is near at hand. A division of 

 the cell contents ensues, so that there now appear rows of 

 cells divided into portions nearly square in outline, densely 

 filled with protoplasm and chlorophyll and containing in gen- 

 eral four pyrenoids. 



Long filaments composed entirely of zoospore mother- cells 

 are frequently found, either detached or forming continuations 

 of the Pilinia branches. An instance of this was noted in a 

 hanging drop culture. Instead of occupying the terminal 

 region of a Pilinia branch, the reproductive cells extended 

 200 mic. in length and were limited at each end by ordinary 



