Fune 4, 1885] 
NATURE. 
TOl 
resources and industries of the State precedes the cata- 
logue of minerals. This, though interesting matter, seems 
rather out of place. H. B. 
ALGE 
Rabenhorst’s Kryptogamen-Flora von Deutschland, 
Oesterreich, und der Schwetz, Zweiter Band. Die 
Meeresalgen. Bearbeitet von Dr. F. Hauck. Nos. 7, 8, 
9,10. 8vo. (Leipzig: Ed. Kummer, 1883-1885.) 
A Monograph of the Alge of the Firth of Forth. By 
George William Traill. 4to. (Edinburgh: Printed for 
the Author, 1855.) 
Notes on Marine Alge. By Edw. Batters, F.L.S. (Pro- 
ceedings of the Berwickshire Naturalist Club, 1884.) 
ale concluding numbers of Dr. Hauck’s work have 
recently appeared. To the description of species is 
added an appendix in which some new species are de- 
scribed. Then follow a comprehensive key to the genera ; 
an index of families, genera, species, and synonyms ; lists 
of illustrations, and of works on algz, arranged alphabeti- 
cally, according to the names of the authors; also the 
title-page, preface, and table of contents—all most useful 
auxiliaries to a scientific work. 
To the favourable opinion of this work, already ex- 
pressed in the columns of NATURE (vol. xxix. p. 341), it 
may be added that the later numbers, treating of the 
Chlorozoosporez and the Schizophycee, fully justify this 
opinion, and Dr. Hauck must be congratulated on the 
successful completion of what has undoubtedly been an 
arduous undertaking. 
In turning over the pages of the work, one cannot but 
be ‘struck by the variety of views which, in spite of the 
closest examination by competent observers with the aid 
of the best microscopes, still prevail among algologists as 
to the systematic position of certain alge. 
Not to multiply instances, it will be sufficient to mention 
the genera Porphyra and Bangia. By Dr. Berthold and 
Dr. Hauck they are classed with the Floridez ; while 
Dr. Agardh and M. Rosanoff place them among the 
Ulvacez. As to Goniotrichum, which Dr. Agardh rele- 
gates to the Ulvacez and Dr. Berthold includes in the 
Bangiacee, Dr. Hauck, in despair of discovering its 
affinities, places it at the end of the description of species, 
as of still doubtful position. 
Although it may be doubted whether all Dr. Hauck’s 
identifications of British Algze will be admitted by our 
botanists, yet the work cannot fail to prove extremely 
useful in this country, and is, in fact, much needed. 
Mr. Traill’s work, entitled “ A Monograph of the Algze 
of the Firth of Forth,” consists of an alphabetical list of 
the marine Algz of this locality, with their habitats, time 
of appearance and of fruiting, and the names of the host- 
plants on which grow such species as are epiphitic. Each 
copy of the work is intended to be illustrated with some 
half-dozen herbarium specimens of the rarer Algae. Those 
in the copy before the writer are in excellent condition, 
and are interesting from their rarity. 
That Mr. Traill is a most patient and painstaking 
observer goes without saying. An analysis of the list 
will show how many species he has collected and ob- 
served, which are new, not only to the Firth of Forth, but | 
to the British marine flora. He has watched the growth 
and development of these plants from their first appear- 
ance until their maturity. Among them will be found 
several Algee which, though frequent in the south, have 
not previously been seen so far north; and he has also 
met with some arctic and northern species which are not 
only new to the British marine flora, but are not described 
in Dr. Hauck’s work. 
Among these northern species may be mentioned 
Phieospora tortilis, which has a range in this country, 
so far as is known at present, from the Firth of Forth to 
Bamborough. While this plant is so abundant in the 
Baltic as to cause much inconvenience to fishermen by 
getting entangled in their nets, its existence is not re- 
corded on the German shore of the North Sea. Uvospora 
Penicilliformis, one of the Algee found by Dr. Kjellman 
on the coast of Spitzbergen, is another of Mr. Traill’s 
“ finds.” 
It will be observed that he mentions having obtained 
the cystocarps of Rhodymenia palmata. If he has really 
met with the true crystocarps of this plant he is for- 
tunate, since Dr. Agardh, Dr. Harvey, Dr. Hauck, and 
other botanists have hitherto searched for them in vain. 
Harvey has shown (“Phyc. Brit.,” Pl. 217) that bodies 
outwardly resembling cystocarps are common enough ; 
probably these are what Mr. Traill has found. They are 
not, however, true cystocarps. 
The establishment of the Biological Station at Granton, 
near Edinburgh, will certainly give a fresh impetus to the 
study of marine botany in that locality ; and there is no 
doubt that Mr. Traill’s work will be found extremely 
serviceable to local collectors of Algz. 
The Proceedings of the Berwickshire Naturalist Club 
for 1884 contain notes by Mr. Edward Batters on seven- 
teen species of rare and little known Algz found by him 
at Berwick-upon-Tweed. A short and clear description 
is given of each species, and the rarer kinds are illustrated 
by lithographic plates. 
LETIERS TO THE EDITOR 
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of communications containing interesting and novel facts.| 
Ocular After-Images and Lightning 
Ir will no doubt be of interest to many of your readers to 
know that the curious optical phenomenon observed by Prof. 
C. A. Young, when working with a large Holtz machine, and 
referred to in Mr. Newall’s letter (NATURE, vol. xxxii. p. 77), 
may be produced with very small apparatus. 
1 have in my possession one of the small Voss machines with 
10-inch plates which are now so common. Upon the stand of 
| this instrument I placed two ordinary Leyden jars, about 
54 inches high, in such a position that their tinfoil-covered 
bottoms touched the brass sockets in which rest the fixed con- 
densers of the machine, while the rods connected with their 
inner coatings were in contact with the sliding electrodes ; with 
this arrangement sparks of great brilliancy from 14 to 2 inches in 
length could easily be produced at the rate of about six per 
minute. A copy of NATURE was set up against a dark back- 
ground 4 feet distant from the machine, and at every discharge 
the paper appeared to be illuminated by two, or sometimes 
three, distinct flashes of decreasing brightness, which succeeded 
one another with great rapidity. Each flash was sufficiently 
