QUARTERLY CHRONICLE OF MICROSCOPICAL SCIENCE. 291 



growth. The middle links of the series, the Sphacelariece , 

 and the genera Halnpteris, Stypocaulon, &c., are more and 

 more differentiated in their structure, and, in the morpho- 

 logical distinctions of their systems of ramification, almost 

 step by step approach the bud-like jointing and the 

 structure of Cladostephus. Thus the manner in which the 

 Sphacelaria-sevies attains in Cladostephus its more distinct 

 and established cormophytic configuration, seems well suited 

 to illustrate certain correlations between the anatomical 

 structure, the origin, and the configuration of the systems 

 of ramifications. As the basis for the comparison, Pring- 

 sheim copiously describes two of the links in the Sphace- 

 laria-series in respect to their structure and the development 

 of their systems of ramification ; Cladostephus verticillatus 

 as the most perfectly differentiated link in the series, and 

 Sphacelaria olivacea as one of the lower forms in which the 

 differentiation of the ramification has scarcely advanced. 



The first differences which occur in the forms of ramifi- 

 cation in this series, commencing with the conf'ervoid type, 

 are presented, by the formation of the fruit, and begin vege- 

 tatively by the formation of trichoma-like apices and iode- 

 pendent trichomata. Both appear only as portions of branches, 

 originally uniform, but checked and modified in their growth. 

 In a further stage entire branches suffer these modifications. 

 Further differences afterwards appear between the purely 

 vegetative branch- forms. In this stage (of which the Sphace- 

 lariecs proper present numerous examples) we meet with 

 branches close together, in some of which the growth be- 

 comes extinguished earlier than in others. By degrees these 

 differences increase in Chcetopteris, Halopteris, Stypocaulon. 

 Still later further differences amongst the limited and un- 

 limited ramifications become more definitely distinguished, 

 and the systems of ramification in the final link of the whole 

 series, the genus Cladostephus, become sharply separated 

 into the different modifications of branch and leaf-forms. 

 A distinct connection of the morphological configuration 

 with the structure and the origin of the bud-formation does 

 not admit of being overlooked. 



The first indications of a differentiation in the ramifications 

 occur in the purely confervoid Ectocarpus-species, which 

 still show no kind of differentiation of their tissue. These 

 morphological distinctions only become noticeable with 

 the distinct separation of the tissue into permanent and 

 formative cells, and especially with the advancing localisation 

 of the latter at the apex of the thallome, and with the 

 separation of the tissue of the axis into central and peri- 



