Nr. 1] SUBAÉRIAL ALGAE FROM SOUTH AFRICA 



fiature, to be found in all species of the saniple, must be attributed 

 to a comnion origiu, possibly being due to exlemal conditions. 



The cells are iiuicli inflated, l)i()adly elliplic to nearly globose, 

 17—22 // broad, and willi a broadth of the conslrictod nodes of 4 — 7. 

 on on average 5 — 6 u. PI. VIII will lurther give au idea of their 

 shape. 



The inner structure of the cells is not easy to examine exactly 

 in a material so incoinplote and insufficiently prepared. The chro- 

 niatopliore, however. consists of long and narrow ribbons, one or 

 several m each cell conforming to the pictures of Karsten. At 

 times, these ribbons break up in several small j)arielal discs. A 

 ])yrenoid is wanthig. 



This species seems to be an subaeiial alga widely spread in the 

 tropics, as it has been found in the troi)ical regious of the new as 

 well as the old world: Chili, Costa Rica. the Dulch l^ast Indies, Au- 

 stralia, and now in South Africa. Although it has been observed and 

 exaniined in course of time by several investigators in nature as 

 well as in cultures, it has always been recorded as sterile, its repro- 

 ductiou. accordingly, having been hitherto unknown. It is particular- 

 ly interesting then, that in one of the samples examined I have found 

 the rei)ro(hiclive organs of this species (in a samjile from densc 

 wood above Bluff, along the cross-road to the South African Whaling 

 Com])any"s station, Nov. lotli, no. 120). Its sporangies are formed 

 from ordinary vegetative cells in their swelling to somewhat larger 

 ilimensions and assuming a nearly spherical aj)pearance. The 

 breadth of tlie sporangies I have found to be 25 — 31 u. Every vege- 

 tative cell seems to be able to grow out into a sporangium; for the 

 sporangies grow out quite arbitrarily.singly.two or several in series, 

 intercalary or apical, and occur anywhere on the thallus. Now 

 there appears something very interesting, viz. that the spores 

 formed, are surrounded by a thin, but distinct membrane. Thus, 

 thev are not zoospores or gametes, as might be expected in a 

 Trciitepohlia. but real aplanospores. They are globose. and measur.- 

 7—11 (/ in diajueter, and arise in a number of 4 — 10 in each aplano- 

 s]>orangium. As is characteristic of this species on the whole, their 

 membranes are also delicate, and on account of the mutual compres- 

 sion when lying within the mother membrane, they become some- 

 what angular, as it may also be seeu that the thin mother mcjnbranr 

 in placcs is bowed out owing to the pressure. which is caused by 

 them. PI. XIII, fig. 30(3. The aplanospores are liberated througli 

 an opening in the wall of the sporangium (fig. 308 and 310). In the 

 dried material at my disposal I have not been able to examine 

 exactly the inner structure of the aplanospores, as also their fate 

 after leaving the mother membrane is still an misolved problem. 

 This ought. by the way. preferably to be examined in fresh and 

 living material and in pure cultures. The formation of aplanosporeti 



