674 SUMMARY OF CURRENT RESEARCHES RELATING TO 



Colouring-matter of Sphagnacese.* — According to M. F. Gravet, the 

 red or orange colonring-matter of the male branches and of the capsules 

 of the different species of Sphagnum is caused by the presence of tannin, 

 produced under the action of light, although the male branches are also 

 coloured even when growing in the shade. 



Algae. 



Vacuoles in Algse.f — Herr F. A. F. C.Went describes the occurrence 

 of vacuoles in the reproductive and propagative organs of a number of 

 Algae belonging to the Floridese, Fucace^e, Phseosporeaa, Cladophorese, and 

 Codieae. He finds them to agree with those previously observed in the 

 vegetative organs, in the presence of a living tonoplast, and in the fact 

 that the normal vacuoles invariably result from the division of those 

 already in existence. The organs in which they were detected are, 

 among others : — the sporanges of Codium, the zoospores of Chsetomoi-pha, 

 the sporanges of SporocJinus, the oogones and antherids of Cystosira and 

 Sargassum, the tetraspores, pollinoids (spermatia), and carpospores of 

 several Floridese, and many others. 



Antherids and Pollinoids of Florideae.J— M. L. Guignard continues 

 his account of the male sexual elements in Cryptogams with a study of 

 these organs in the Florideae. Their structure and mode of origin are 

 in general terms the same throughout the class. The antherid either 

 springs directly from a single cell of the thallus, or results from more 

 or less numerous bipartitions of the antheridiferous cell. The poUinoid 

 is a round or ellipsoidal body, not absolutely naked, but inclosed in a 

 very thin investment, which does not, however, give the reactions of 

 cellulose; it escapes by the gelification of the apex of the antherid. 



In Batrachosjyermum, Nemaleon, and Helminthora, we find the simplest 

 structure and arrangement of the antherids, which spring by budding 

 from the extremities of peripheral filaments of the thallus. Each poUi- 

 noid has a nucleus, but no nucleole. In Callitliamnion roseum the struc- 

 ture is no way essentially different. In Griffithsia corallina the antherids 

 are developed at the extremity of particular branches of the thallus, in 

 the form of tufts. 



In Polyides rotundus the antherids are formed in tetrads on filaments 

 resulting from the prolongation of cortical cells. Their mode of forma- 

 tion recalls that of tetraspores, or even of the pollen-grains of flowering 

 2)lants. In CJiondria tenuissima the antherids result from the trans- 

 formation of hairs which cover the branches, and are produced in a 

 dense row. 



In the Melobesiacefe and Corallinacese the form of the antherids and 

 pollinoids is very remarkable. In Melobesia memhranacea the male con- 

 ceptacles are clothed with hairs, each of which becomes segmented into 

 a row of antherids. The greater part of the contents of each antherid 

 contracts into a poUinoid, each of which, when it escapes, is furnished 

 with two appendages having the appearance of wings, the remains of the 

 walls which divided the filaments into antherids. In Corallina officinalis 

 the antherids are produced in tufts, and are of a very elongated club- 

 ijhape ; and the poUinoid, when it escapes from the antherid, is an oval 



* Rev. Bryol., xvi. (1889) p. B7. 



t But. Ztg., xlvii. (1889) pp. 197 206. Of. this Jom-nal, 1888, p. 98J. 



* Hcv. Gcii. tie Hot. (Bonnier), i. (188'J) pp. 17.3-86 (1 pi.). 



