MARINE AI.GAE FROM EASTER ISLAND 



273 



A. Kalt'siac now spec. — Fig. 18, 19. 



Thallus caespitulosus, V2 — 1 mm altus, e filis endophyticis robustioribus 

 moniliformibus et filis erectis liberis tenuioribus compositus. 



Fila endophytica inter assimilatores hospitis (Ralfsiae rxpansac) immersa, 

 ramosa, plus minus aggregata, e cellulis subglobosis-ovalibus, long. 20—22 »j., 

 lat. 16 — 20 [j. composita. 



Fila libera erecta versus apicem gradatim attenuata, e cellulis cylindricis, 

 7 [i latis et 18 — 20 — 27 [j. longis composita, statim a basi sparse et irregulariter 

 ramosa. Rami aut longiores pluricellulares, aut unicellulares sporangiferi. 



Sporangia oblonge-lanceolata, 9— 12 u. lata et 17 — 20 u, longa. 



Hg. 18. A'crochaefimn Ralfsiae now spec. Basal parts, in a immersed into the tissue of the 



host. C. 300 /i. 



On a dried specimen of Ralfsia expansa this Acrochaetium was growing 

 in great numbers, having a vigorously developed basal part of the thallus im- 

 bedded in the tissue of the host plant. 



This endophytic basal part (Fig. 18 a and 19 a) consists of large cells 

 mostly as long as broad or a little longer; their diameter is 20 {J.; they are 

 often swollen in the middle, the endophytic filaments thereby getting a monili- 

 form appearance. The cell wall is very thick. The filaments are as a rule 

 vertically arranged, the branches growing out at acute angles and more or less 

 parallel with each other, but often also somewhat bent, finally forming a bundle 

 in the tissue of the host. Arrived at the surface or a little above the fila- 

 ments quickly decrease in size at the same time generally developing a few 

 side branches. 



The filaments in the free part of the plant are about 7 u. thick and the 



cells 20—27 ul long. The filaments now and then carry a side-branch, but as 



a rule they are not much branched. The branches are sometimes seriate but 



mostly without any order. Some of the branches may grow out to long filaments 



18 — 2381. The Nat. Hist, of Juan Fernandez and Easter I si. Vol. II. 



