On the Pithophoeaceje. 



35 



V. ON THE AFFINITIES OF PITHOPHOEACE^E AND THE PLACE OF 



THIS OEDEE IN THE SYSTEM. 



If we regard, at first, only the vegetative system, we easily find 

 a group of plants which in this respect shows a very close affinity to 

 Pit hop] i or ace a'. Already the circumstance that the forms now found to 

 belong to the new order of Pithophoracece, which have formerly been 

 described in floristic works, have all been described as species of the genus 

 Cladophora, *) gives an unmistakeable hint on this head. The resemblance 

 between Pkhophoracece and Cladophorece as to the vegetative system is, 

 in fact, very great. In both, the thallus consists of cylindrical chloro- 

 phylliferous cells, connected so as to form a ramified series of cells; in 

 both, the formation and increase of the cells, as well as of the series 

 of cells, takes place essentially in the same manner; in both, the deve- 

 lopment of branches follows in general the same law; 2 ) and in some 

 Cladophorece organs even occur which are of the same nature as the 

 helicoids of Pithophoracece. :i ) The resemblance as to the cauloid part 



l ) Only one author, Gbunow, has had a conception, that one of the forms 

 commonly referred to the genus of Cladophora ought perhaps to be aggregated to a 

 genus-type separate from Cladophora. This author says in »Reise S. M. Freg. 

 Novara» pag. 89 of Cladophora Rodtleri (Roth) Kiitz. (= Pithophora Roettlcri 

 nob.): »Von Roth als Ceramium beschrieben, verdient diese Art vielleicht einmal 

 bei genauerer Kenntniss der" Cladophora-nrterx als eigene Gattung davon abgeschieden 

 zu werdenw. In the same place he also pronounces his opinion on the probable origin 

 of the spores (»Fruchtzellen») of this Cladophora t.hus:» In einigen Fallen beobachtete 

 ich (in :i brasilian form) Fadefi mit spatelformig angeschwollenen Astenden mit ge- 

 hiiuften Chlorophyll-Inhalt, aus denen sich durch Abschniirung die Fruchtzellen zu 

 e n t w i c k e 1 n scheinen.)) 



-) Compare v. Mohl, Verm. d. PHanzenz., pages 363 and 366, pi. 13 (on 

 Cladophora glome rat a ) . 



3 ) J. M. Lohentz represents in Die Straton. v. 2P(jciyr. on pi. 4, figs. 14 and 

 15 parts of the thallus of 2Egagropila Saidcri, where two of the terminal cauloid 

 cells have assumed, by the formation of small processes at their top, almost the same 

 forms as those common in the helicoids of P. Cleveaiia nob. As these top cells also 

 serve the same purposes as the organs of Pithophoracece, 1 do not hesitate to regard 

 them as real helicoids. They arc, like the helicoids of Pitjwphora, very rich in chloro- 

 phyll, but not only in their upper and ramified part, but also in the lower. In 

 Kutzing, Tab. Phyc, Band 4, pi. 66 a representation is given of JEyagropda her- 



