Jan. lo, 1889] 



NA TURE 



251 



Dr. Askenasy prefaces his description of H\lim;da by 

 remarking that the structure of the genus has rvT. bian 

 hitherto described. From this it would appeir that Dr. 

 Agardh's observations on Halimeda, contained in Part V. 

 of his work, " Til Algernes Systematik" (" On the Classi- 

 fication of Alga;"), is still unknown at Berlin. It may be 

 mentioned that, while the title is in Swedish, the work is 

 in Latin. 



The remarks of Dr. Askenasy are, however, not the less 

 welcome, illustrated as they are by the figures in Plate IV. 

 One new species, H. macrophysa, is described. It is to 

 be regretted that so little is as yet known of the fructifica- 

 tion of these plants. 



One new species of Caulerpa, C. delicafula, allied to 

 C. BroTcnit, is added to the sixty-seven species of this 

 genus already known to science. 



The Ectocarpeiie are carefully worked up, and one new 

 species from Kerguelen's Land, E. Constantice, has been 

 added by Dr. Hariot. 



Perhaps the most interesting part of the work is the 

 result of Dr. Grunow's study of the genus Sargassum. 

 Every algologist is aware how difficult it is to identify the 

 specimens, often very fragmentary, of this plant, which lie 

 before him for examination. Fortunate is the collector 

 who obtains a whole plant of Sargassum, comprising root 

 and lower leaves — which often differ materially from those 

 in the upper part of the plant — branches bearing leaves 

 only, and other branches bearing fruit and vesicles as 

 we'l as leaves. It is owing to this fragmentary state of 

 the plants that the published descriptions are frequently 

 defective. 



Dr. Grunow has done much to elucidate the life- 

 history of the genus Sargassum by his discovery that some 

 species are moncecious, and others dioecious. In describ- 

 ing 5. Carp •pJtyllun (see " Voyage of the Novara" p. 56), 

 Dr. Grunow mentions the occurrence on the same plant 

 of two kinds of fruit — namely, short receptacles which 

 correspond with those described by Dr. Agardh, and also 

 linear receptacles three-quarters of an inch long. He, 

 however, makes, in this work, no further observations on 

 the subject. 



In the present work he merely mentions that the plant 

 is moniecious. It will be seen from the descriptions of 

 the other species in the text that Dr. Grunow has been 

 able to prosecute successfully his researches on the fruit 

 of the Sargassa. In most cases it is indicated in the text 

 whether the species are monoecious or dioecious. It seems 

 to be ascertained that the smaller kind of fruit contains 

 spores ; while the antheridia are contained in receptacles 

 nearly twice the size of the former. There also exists much 

 diversity in the form of the receptacles belonging to the 

 same species. The spore-bearing receptacles are some- 

 times forked or spiny, while those bearing antheridia are 

 simple, smooth, and cylindrical. The list of Sargassa in 

 the present work contains twenty-eight species and 

 varieties. In the case of the varieties Dr. Grunow is 

 careful to mention in what respects they differ from the 

 original species. 



As to .V. bacciferuin, it is mentioned in the text that its 

 history is still insufficiently known. The editor refers 

 to the pelagic specimens, called "gulf-weed," which float 

 for a time without root or fruit, and subsequently decay ; 

 but he does not seem to be aware the S. bacciferum was 

 found by Mr. Moseley,' during the voyage of the Challenger, 

 growing plentifully and full of fruit on rocks in Harrington 

 Sounc^, Bermudas. The S. bacci/erum, war. folu/era, also 

 bears fruit. 



It may be remarked that while there is a general im- 

 pression that no parasitic Algae are found growing on gulf- 

 weed, Dr. Askenasy met with a specimen among the 

 Algae brought home by the Gazelle on which were growing 



1 See ext-act from Mr. Nioseley's letter, dated June 27, 1873, in Dr. Dickie's 

 paper on ihe marine Alg.x of St. Ihomas and Bermuda, Jcumal cf the 

 Linnean So:i.ty, vol. xiv. 



a Rivularia and a Calothrix, and that other epiphytic 

 AlgfE were found on the same species by Martens. 



Among the Rhodophycea: of this collection, there is 

 one new genus, Episporium centroceratis, Moebius. It is 

 from West .Australia, and is classed with the Crypto- 

 nemiaceae. The new species are four in number — namely, 

 Hildebrandtia Lecaiinellieri, Hariot ; Chaukansia Nau- 

 manni, Askenasy ; Rhabdonia decumbena, Grunow ; and 

 Sarcomenia intermedia, Grunow. Among the rarer 

 species are CorynosporaWiillcrstorJiana, Grunow; Ptilota 

 Eaioni, Dickie ; and Marchesettia spongioides, Hauck. A 

 plentiful harvest was obtained of the beautiful and very 

 rare Nitophylla and Delesserica; of the Southern Ocean. 



The attention of algologists will be drawn to the minute 

 and careful analytical descriptions of many species of the 

 Floridea:. Great pains have been bestowed by Dr. 

 Askenasy on the description of some species of Galaxaura: 

 the more delicate parts of these plants, he observes, have 

 not been described. Fruit is rare, and but imperfectly 

 known in this genus. It may be observed that Dr. 

 Askenasy's classification of Galaxaura differs from that of 

 Agardh ("Til Algernes Systematik," Part vii., Florideae). 

 By the former it is placed arnong the Cha;tangiaceae ; the 

 latter retains it among the Helminthocladieae. 



Dr. Askenasy gives an elaborate description of that 

 singular production of Nature, Marchesettia spongioides, 

 Hauck. He mentions it as " this plant or organism," for 

 it seems to be between a Sponge and an Alga. It was 

 known imperfectly to Semper and Esper. Dr. Hauck, 

 who had found it among the Sponges in the Museum at 

 Trieste, announced that it was an Alga, which belonged 

 to the Florideae, and to the group of the Areschougieae 

 (" Su un nuovo caso di simbiosi," Atti del Miiseo Civ. di 

 Stor.Nat.di Trieste, 1884). In external appearance this 

 "organism" resembles a branched Sponge; the Alga 

 being entirely inclosed within it. Dr. Askenasy has 

 devoted one whole plate (Plate XII.) to illustrate the 

 Marchesettia. The fructification is at the end of the 

 branches. Tetraspores were seen by Dr. Hauck and 

 by Dr. Askenasy, but it is not mentioned whether 

 they were cruciate or zonate. Dr. Agardh observed 

 cystocarps, which he thought approximated to those of 

 Rissoella, 



On the inside of the' " organism," and among the 

 branches of the Alga, Dr. Askenasy found, in the speci- 

 mens brought home by the Gazelle Expedition, and pre- 

 served in spirit, a slimy substance, like that which con- 

 stitutes the life of a sponge, and he is decidedly of opinion 

 that Marchesettia spongioides is, to use his own words, 

 " eine symbiose zwischen einer Floridee und einer 

 Spongie darstellt" (p. 41). Marchesettia is a native of 

 Madagascar, Singapore, the Philippines, and New Cale- 

 donia. 



The external resemblance of the Marchesettia to a 

 species of Thamnoclonium of the section Dictyophora; 

 is so great that Dr. Agardh gave to the latter the name of 

 Th. Marchesettioides. The plants, when in fructification, 

 may, however, be always easily distinguished, the fruit 

 of the Thamnoclonium being contained in leaflets, which 

 spring from the sides of the plant. 



This is a very useful wrrk to alg. logists ; but its utility 

 would have been increased by the addition of an index. 

 It may also be observed that the size of the type might 

 have been enlarged with Leiiefit to the ey s of students. 



The subject of Dr. Agardh's essay is the structure of 

 Champia and Lomentai ia. He observes that within the 

 space of little more than a year, four special essays— two 

 by N. Wille, one by F. Debray, and another by R. P. 

 Bigelow — have been published with a view to demonstrate 

 the structure of these well-known plants, and that these 

 publications give an entirely erroneous representation of 

 the entire development of these Alga;. He therefore 

 thought it expedient for him, who had published ten years 

 ago a very different description, to state his opinion on 



