82 



HARDWICKE'S SCIENCE-GOSSIP. 



to abandon the generally received idea of the grain 

 of sand which plays the part of the crumpled rose- 

 leaf to the molluscous sybarite, and concludes, from 

 observations made on the marine mussel {mytilus), 

 his conclusions being supported by the independent 

 researches of Signor Antonio Villa, in Italy, that 

 the exciting cause is no inorganic particle, but is 

 actually a minute parasitical entozoon (a species of 

 dlstoma) in the mytilus ; while in the anodon, or 

 fresh-water mussel, it is a minute mite, or acarus 

 {Atax) — in fact, an itch insect. The presence of 

 such parasites as a nucleus he has proved by treating 

 the pearls with a dilute acid. Mr. Garner then 

 hints at the possibility of setting on foot a kind of 

 pearl nursery, so to speak, where the cultivation of 

 this precious ornament may be carried on ; citing 

 the Chinese as an example, who, as is well known, 

 not only introduce metallic figures of Buddha 

 between the shell and mantle (there to be pearl- 

 washed by the mollusc for the ultimate benefit of 

 the faithful), but even go so far as to bring about 

 what may be termed a "margaritiferous" diathesis, 

 by contaminating the water inhabited by the mussel. 

 With regard to such diathesis, it may be interesting 

 to mention a theory of a celebrated French zoologist. 

 M. Lacaze-Duthiers put.forward some years ago, in 

 the Annales des Sciences Naturelles, that a mollusc 

 so affected is in the condition of a calculous or 

 gouty subject, its blood being highly charged with 

 the material which goes towards the secretion of 

 pearly substances; the excess of which over and above 

 what is required for the nacreous lining of the shell 

 is precipitated in the form of a pearl, much as in the 

 analogous case of a man a calculus is formed in the 

 kidney or bladder, or a concretion of urate of soda 

 above the knuckles. 



RARE LIVING OBJECTS. 



A T a recent monthly meeting of the Microscopic 

 -^^ Society of Liverpool, Captain John A. Perry, 

 associate of the society, exhibited two living diamond 

 beetles {Entimus nobilis) -. these he had procured at 

 Rio de ; Janeiro, Brazil, and they were unusually 

 large] and brilliant. They are doubtless the first 

 living specimens ever brought to England — if not to 

 Europe — and were specially obtained for the 

 purpose of being exhibited alive to the society. 

 There had been great difficulty in keeping them 

 alive, on account of the great difference of 

 temperature between the Brazils and England. 

 These beetles were taken from their native 

 clime during the height of the Brazilian 

 summer (Januai'y), with the sun nearly vertical, and 

 the thermometer registering 110° Fahr. in the shade 

 out of doors the day they were procured ; whereas 

 in England at the time they were exhibited, the 



thermometer indoors was about 38° Fahr. Captain 



Perry has been also successful in bringing home, on 

 previous voyages, many rare livi7ig fish, most of 

 which have not before been seen alive in Europe. 

 They included one Pomotis (?) ,tw eh eFcecilia uuima- 

 cidata, and seven of a species new to science, called 

 by the natives Cam. The above are from the 

 Brazils, and from the Rio de la Plata. He has also 

 succeeded in bringing honiethirteen living GaZ/jc^^/z^i' 

 asper, and two Firamutana Blochii. All these fish 

 (many others having died during the voyage) were 

 brought home expressly for the aquarium of the Free 

 Public Museum, Liverpool, where they lived for 

 some time, until attacked with a fungoid growth, 

 which has from time to time killed them ofi", so that 

 at the present time, out of the thirty-five brought 

 home alive, not one remains. Captain Perry is 

 quite 'prepared, as the warm weather sets in, to 

 bring home others ; having already secured a stock 

 in a healthy condition at Rio de Janeiro. The fun- 

 goid growth that attacked and killed the above 

 fish, as also many other valuable foreign fish 

 belonging to the Museum, was the subject of an 

 interesting communication by the Rev. Mr. Bannis- 

 ter, at the meeting of the Microscopical Society, 

 which was discussed by the Rev. Mr. Dallinger and 

 other members. Mr. Dallinger had devoted some 

 time to the study of this particular fungoid growth, 

 which he found to be not only superficial, but to 

 ramify into the flesh and even into the vitals of the 

 fish. Many of the readers of Science-Gossip are 

 also indebted to the above gentleman (myself among 

 the number) for portions of his Porto Seguro and 

 Rio de Janeiro gatherings, both of which were rich 

 in rare and beautiful species of Diatomace«e. 



F. KiTTON. 



HERBARIA. 



ALTHOUGH various have been the sug- 

 gestions made by the students of botany with 

 regard to the construction of an herbarium, it 

 seems somewhat strange that the not less import- 

 ant matter of mounting the specimens should have 

 been so generally overlooked ; for, as a rule, where 

 any reference at all has been made upon the sub- 

 ject, I have observed that paper has, in most 

 instances, been the material recommended for this 

 purpose. At this I cannot but express my surprise, 

 especially since I have learned, by experience, that 

 no plant of such delicate structure as those found 

 comprising an herbarium can well be preserved 

 from injury on so thin a substance ; and this, I 

 think, will become the more apparent when the 

 extreme crispness of plants in their dried state is 

 considered, and how, therefore, they are the more 

 easily rendered imperfect by the slightest of causes, 

 but which is most frequently of all due to the 

 neglect of so apparently a minor point as the one 



