August ii, 1910J 



NATURE 



171 



and this was again modified in 1909. Certain statis- 

 tical information given is, too, of doubtful correct- 

 ness. Names are frequently misspelt. But putting 

 aside minor blemishes of this kind the work is of a 

 decidedly useful nature, and, like the inorganic portion, 

 to be commended. It may be noted that a German 

 translation of the whole work is in progress, so that 

 it may shortly become more accessible to the English 

 student. W. A. D. 



OVR BOOK SHELF. 

 Ciiide to the Crustacea, Arachnida, Onychopliora, and 

 Myriopoda exhibited in the Department of Zoology, 

 British Museum {Natural History). Pp. 133; go 

 illustrations. (London : Printed by order of the 

 Trustees of the British Museum, 1910.) Price is. 

 This "Guide" admirably fulfils its functions; it is 

 written in a clear style, and indicates tersely the main 

 points of interest associated with the chief families 

 and genera. The principal characters of each sub- 

 division — class, order, tribe, family — are concisely 

 stated, and those of its members are selected for 

 mention which most aptly illustrate points in 

 morphology or distribution, or show some striking 

 habit. The section on the Crustacea opens with a 

 short account of the lobster, its external features and 

 -appendages, internal organs, development, moulting, 

 and the asymmetry of its chelae. Short notes are 

 added on the modifications caused by parasites and on 

 adaptations to environment. 



The systematic account of the Crustacea, in addi- 

 tion to stating the characters of each subdivision, 

 contains a large number of interesting references to 

 morphological and distributional points which make 

 It valuable apart from the special purpose for which 

 it was prepared. To give two instances — (i) the 

 formation of a respiratory siphon which takes place 

 in the .\lbuneidae by apposition of the antennules, but 

 in Corystes by association of the antennae ; and (2) 

 the appearance of Apus in Scotland in 1907, which is 

 ascribed to the introduction of the eggs, per- 

 liaps on the feet of birds, from the Con- 

 tinent. The Arachnida, including Limulus and 

 the Eurypterines, and the Myriopoda are dealt 

 ■with in a similarly interesting manner, and short 

 notes are added on the Trilobita, Pycnogonida, Penta- 

 stomida, and Oncychophora. A little more space 

 rhight well have been devoted to the I.xodidae, in view 

 of their great importance in connection with the spread 

 of disease in man and animals. The illustrations, 

 ■many of which are new and are prepared from photo-' 

 graphs of the specimens exhibited, are excellent, and 

 ■well support the text. 



Popular .Astronomy. By the late Prof. Simon New- 

 comb. Pp. XX -I- 580 + 5 star maps. (London: Mac- 

 millan and Co., Ltd., 1910.) Price 8x. 6d. net. 

 Astronomy has no doubt made progress in several 

 directions since the late Prof. Newcomb revised his 

 renowned work; nevertheless, if the lamented author 

 were alive to re-write his book at the present time, by 

 far the greater part could not be improved upon. The 

 extensions of knowledge take place at the frontiers 

 of a science, while the main bodv of fact and prin- 

 ciple remains unaltered. While, therefore, this cheap 

 edition of Prof. Newcomb's " Popular Astronomy " is 

 issued without additions? referring to recent develop- 

 ments, the volume can fairly be described as one of 

 the most lucid and authoritative statenients of the 

 foundations of astronomical science available even 



NO. 2128, VOL. 84] 



now. To let such a work pass out of print would 

 have been a misfortune, and we trust that the issue 

 of an edition at less than half the original price will 

 be the means of making many new readers familiar 

 with its merits. 



Naturu'issenchaftliches UnterricMswerk fiir hohere 



Mddclienschuleii. Teil iv., Lehrstoff der iv. Klasse. 



By Dr. K. Smalian and K. Berm.au. Pp. 



152. (Leipzig : G. Freytag, 1910.) Price 2.50 



marks. 

 This volume, one of a series graded for successive 

 school classes, has been prepared to comply with 

 official regulations, wherein presumably lies the reason 

 for combining a triad admixture of botany, zoology, 

 and mineralogy. The aim of the authors has been 

 directed less towards a training manual and 

 more towards providing a compendium of in- 

 formation on objects which are met with in daily life. 

 The book contains an accurate but condensed collation 

 of facts concerning cryptogamic and economic botany, 

 the zoological groups of moUusca, vermes, and coelen- 

 terata, and common or useful minerals. It is plenti- 

 fullv illustrated with good text-figures and a dozen 

 coloured plates. 



LETTERS TO THE EDITOR. 

 [The Editor does not hold himself responsible for opinions 

 expressed by his correspondents. Neither can he undertake 

 to return, or to correspond with the writers of, rejected 

 manuscripts intended for this or any other part 0/ Nature. 

 No notice is taken of anonymous communications.] 



Pwdre Ser. 



In my former communication on this subject I gave all 

 the information I had been able to collect respecting the 

 popular belief as to the masses of white jelly found in my 

 experience on mountain pastures, but, according to the 

 observations of others, on different kinds of ground and at 

 \^arious seasons. 



I recently procured a specimen of the jelly, and quoted a 

 letter from' Mr. Arber, to whom I had sent it, giving the 

 opinion of Mr. Brookes, to whom Mr. Arber had referred 

 it. After that was written I received the following note 

 from Mr. Brookes, under the date April 4 : — " The ' jelly * 

 had been gathered several days before it reached me, and 

 hence its condition was not suitable for examination, 

 several putrefactive organisms having begun to flourish 

 upon the jelly in the meantime. The remains of the sub- 

 stance which I saw seemed to be most like the zoogloea 

 stage of some bacterial organism or the Plasmodium of a 

 myxomycete. The ' jelly ' itself had no cellular structure. 

 There was no nostoc present or any allied organism." 



More recently I received a specimen which Mr. Burnett, 

 headmaster of the Grammar School at Kirkby Lonsdale, 

 found in the Rawthay Valley, some miles above Sedbergh. 

 This also I sent to Mr. Brookes, who writes (July 26) that 

 " the jelly-like mass sent from Kirkby Lonsdale is un- 

 doubtedly the Plasmodium of a myxocete," and adds that 

 he is " keeping it to see whether it will give rise to 

 spores." 



Mr. Worthington Smith, in a letter dated June 24, 

 says : — " Perhaps you will find the substance so accurately 

 described by you in this week's N.4TfRE under the generic 

 name of Zoogloea ; the name as a genus may be obsolete 

 now, but I think that in past times it was placed amongst 

 the alga;, perhaps near Nostoc, and afterwards included 

 in the Schizomycetes. However this may be, I know the 

 substance very well, and I have often had it sent on to 

 me in the past (when I used to answer correspondents 

 for some of the horticultural papers) as a fungus — a 

 Tremella — difficult to trace. I have heard it, as well as 

 Nostoc, associated with fallen stars amongst rustics." 



These authorities, as well as Miss Fry (Nature, June 30), 



