134 



HARDWICKE" S SCIENCE-GOSSIP. 



to the group of Polygastric animalcula distinguished 

 by a hard, glassy, bivalve shell, and increased the 

 number of genera in this family by the addition of 

 Cocconema and Syncyclia, and also endeavoured 

 to explain the physiology of the genus Echinella. 

 Moren, in the same year, formed his genus Cruci- 

 genia (Bacillaria ?). In 1831, Agardh published the 

 continuation of his "Conspectus Diatomacearum," 

 and Gray constructed u his genus Biddulphia out of 

 Conferva bidditlphiana and C. obliquata (Isthmia) 

 ("Arrangement of Brit. PL"). 



In 1 83 1 I succeeded, through new observations, in 

 establishing the place of the Bacillaria in the animal 

 kingdom, and added the new genus Euastrum. In 

 1832 Agardh added the new genera Isthmia, Odontella, 

 Striatella, and Grammonema (Fragilaria). In the 

 same year I published a more detailed communication, 

 and increased our knowledge of this family, and also 

 added the genus Xanthidium. In the year 1835 

 Kutzing elaborated a " Synopsis Diatomacearum," and 

 added the new genera Sigmatella (Navicula), Encyo- 

 nema (Monema), Psygmatella (Exilaria), Trochiscia 

 (Tessararthia and Aristella), Epipyxis. He also 

 found by chemical analysis that the hard glassy shells 

 of many of these forms were siliceous, and considered 

 them upon the whole to be plants. 



I made similar researches with the aid of Professor 

 H. Rose, and confirmed these chemical observations. 

 Wallroth was desirous of changing the less happy 

 Latin names of Frustulia and Fragilaria to the 

 equivalent Greek names Rhabdium and TemacJiium, 

 and formed them into a group of plants under the 

 name of Hygrophytozoa. Gaillon in 1834 gave a 

 new synopsis of the Nemazoaires, with many new 

 and very unpleasant generic names for already named 

 forms, and which are now fallen into oblivion. 

 Corda, 1835, also gave many new generic names, 

 which, if more appropriate, are not sufficiently critical, 

 and too trivial in comparison with those already 

 known, to be allowed to remain ; as Pharyngoglossa 

 (Navicula), Cosmarium (Euastrum), Colpopelta (Eu- 

 astrum), Staurastidium (Micrasterias), Sphasrozosma 

 (Odontella), Syrinx (Fragilaria), Paradesmus (Fra- 

 gilaria), Pleurosicyos (Closterium), and Scalptrum 

 (Navicula). The same observer speaks of the existence 

 of oral openings as sexual organs, a thread-like 

 alimentary canal, and even of a tongue in several of 

 the forms, but without stating these supposed facts 

 with any scientific accuracy. He also states he had 

 observed the opening and closing of the shells, but 

 which, however, cannot by any possibility take place. 



Upon the whole he considered these forms to be 

 animals, and not plants, and joins them to the 

 Oscillatoria. In the same year I called attention 

 to the characteristic distinctions obtained from the 

 arrangement and number of the strire. Henle 

 believed that he had observed similar kinds of forms 

 in the internal organs of larger animals. 



Jiirgens gives a list of these forms in his ' ' Flora 



of Nordeney " (1835). Meyen again asserted that the 

 Closteria and Pediastrese were plant cells. 



In further developing the earlier views of the 

 Infusoria, I became captivated by this family. I 

 added (1835) the following genera : Pentasterias, 

 Cocconeis, Pyxidicitla, Podosphcnia, Tessella, and 

 Syncyclia, and in the same year ten plates of this 

 work were engraved, all of which are devoted to the 

 Bacillaria. 



The organisation in this family is, on account of 

 the refraction and hardness of the shells (Panzer), 

 difficult to discern ; but I have by degrees made it 

 out with greater certainty. The characteristic invest- 

 ment (Panzer) is of a varied nature. The group is 

 separated into hard forms, with shells strongly im- 

 pregnated with silica, and membranous forms w ithout 

 silica. (These forms are Desmids and animalcula — 

 F. K.) It is worthy of notice that no calcareous 

 forms have hitherto been detected. 



The external shell is considered by some to be a 

 silicate of iron. Many species have surrounding the 

 siliceous shell a delicate, jelly-like, variously-shaped 

 investment (Frustulia, Schizonema, Micromega, &c). 

 The structure of the Bacillaria is box-like, with a 

 simple ^opening, or two or more shelled with many 

 openings. Among the siliceous forms, a round, a 

 prismatic, or four-sided, and among the non-siliceous 

 a flat, three to five sided shape prevails. 



Organs of locomotion, as tactile organs, are very 

 clearly seen in the Acineta, but they differ very 

 widely from the character of those in the great group 

 Bacillaria. 



I have recently described in the "Transactions 

 of the Berlin Academy, 1837," and added two other 

 genera — Actinocylus and Eunotia. These organisms 

 can only be regarded as the type of a single group, 

 therefore they can only be considered as a partial 

 member of it ; moreover, it is only in the Navicula 

 species that a snail-like foot as a locomotive organ 

 has been observed, and this is rarely projected far 

 beyond the shell. 



It is doubtful whether the mobile granules observed 

 in some Naviculas (as also in the Closteria) belong to 

 this part. The alimentary organ, even by the means 

 of coloured food, has as yet not been detected in any 

 species, but in many of them indications of it may be 

 seen. There are also seen in many of these organisms 

 comparatively large, transparent, variable, colourless 

 globules in the coloured egg mass, which are analo- 

 gous to those in the stomachs of other Polygastrica, 

 and these are what Girod Chantrans imagined (in 

 Naviculas) to be eggs. As the received reproductive 

 organs are in almost all species coloured, on some forms 

 colourless eggs, like granules, are visible. The very 

 fine granular matter is sometimes yellow, brown, or 

 green ; the internal mass is clearly divided into 

 2-4 plates, or tubes, which are united in the 

 central body, as seen in Navicula, Cocconema, 

 Naunema, &c. Sometimes it is piled up in many 



