622 MINNESOTA BOTANICAL STUDIES. 



Upon another point there is disagreement. In his words: 

 "A plate results in which one can distinguish the branch rows, 

 but in the center are found usually cells united like paren- 

 chyma." He illustrates this (PL I, Jig. 3.) Such plates have been 

 seen among the Pilinia material, but not in sufficient numbers 

 to allow of their being designated as a type. In my experience 

 it has been the rule that the cells in the center of the plate 

 (that is, in healthy and rapidly growing young plants) were 

 the first to form branches. Taken as a whole the process 

 of development followed out by the spore in forming the thal- 

 lus is essentially the same as that described by Cienkowsky. 



Fig. 29 shows one plate branch like that in fig. 27, of which 

 the upright filaments have become from 3-4 celled and in one or 

 two cases have branched. PL XXXV, fig. 1, represents a pros- 

 trate branch showing the characteristic bow shape with its 

 accompanying upright filaments. The cells at the apex appear 

 to be producing branches in both planes, i. e. the prostrate 

 branch is still growing while its cells as soon as formed give 

 off the upright branches. An irregular bit of the thallus is 

 protrayed in fig. 2, with some of the lower cells giving off long 

 bristles, and the upright filaments showing clearly their Stig- 

 eoclonium nature. Pig. 3. finally brings to a close the series 

 of forms through which the plant passes from the beginning 

 of germination to the time of fruiting. The figure will be 

 found to closely resemble PL XXXI, fig. 1. Thus the final 

 proof of the unity between Pilinia diluta Wood and Stigeo- 

 clonium flagelliferum Kg. is produced. 



The thalli which were mentioned as growing on the side of the 

 tank toward the light had as their most prominent feature the 

 number and length of the bristles. These rise perpendicularly 

 from the plate, either directly from the basal cells or from up- 

 right filaments composed of several cells. Extensive plates 

 are present with no upright filaments but the bristles. Most 

 of the material, however, has upright filaments. In one in- 

 stance, two bristles are given off by the same basal cell. Some 

 bristles extend horizontally from the plate cells. 



The thalli on the sides of one of the tanks were examined 

 from the outside, with a very low power. Their average diam- 

 eter at that stage was found to be from 50 to 60 mic. The thalli 

 were originally solitary in all cases, as could be seen, and the 

 tendency was to assume a circular shape. When two or more 

 thalli chanced to lie near each other they soon became fused 

 and then an irregular or lobed mass was formed. No filaments 



