October 13, 1892] 



NATURE 



561 



insists upon the importance of detecting it at an early 

 stage, and in the first part of the pamphlet he explains 

 how to do this with cercainty. 



The pamphlet ought to be read by everyone interested 

 in agriculture : and to make it better known the Society 

 has printed as a leaflet a few notes upon the subject. In 

 America the pamphlet would be sent broadcast amongst 

 those interested, and ic is to be hoped that Government 

 i^sistance may soon enable our own Agricultural Society 

 1 disseminate knowledge in a similar way. 



W. T. 



hTU to Make Common Things. By John A. Bower. 

 Society for Promoting Christian Knowledge, 1892.) 



1 would be a strange boy who never wanted " to make 

 . >mething." The present little book has been prepared 

 tor boys who feel this desire very strongly, but do not 

 <]uite know how to set about the fulfilment of their wish. 

 They will here find ample information on the best way 

 of making a vast number of things, from a hat-rail to a 

 galvanometer, from a pair of stilts to a needle-telegraph. 

 The author assumes throughout that those whom he 

 addresses are not being taught by a personal instructor 

 in handicrafts, and that they are not the possessors of 

 an elaborate array of tools. His directions are clear and 

 practical, and cannot fail to be appreciated by boys who 

 find much to interest them in the exercise of ingenuity 

 and manual skill. 



The Student's Manual of Deductive Lo^c, Theory 

 and Practice. By K. R. Bose. (Calcutta : S. K. 

 Lahari and Co., 1892.) 



This book is intended for the use of students at the 

 various Indian colleges, and will be regarded by most 

 teachers of the subject as, upon the whole, a very good 

 text-book. The author has read many of the best 

 European writers on logic, and presents clearly a sum- 

 mary of their results. He begins with a definition of 

 logic, gives some account of its " branches and parts,'' 

 and then considers terms, propositions, and inferences. 

 What he himself describes as "the distinguishing 

 feature " of the book is a collection of problems and 

 exercises with solutions, or hints towards solution, in 

 close correspondence with the subject-matter of the text. 



A Text- Book of Agricultural Entomology. By Eleanor 

 A. Ormerod. Second Edition. (London : Simpkin, 

 Marshall and Co. 1892.) 

 The first edition of this book was published about eight 

 years ago. It consisted of lectures which the author had 

 delivered at the Institute of Agriculture of South 

 Kensington. There was not much demand for it until 

 last year, when attention was directed to it by the ar- 

 rangements of the County Councils for the promotion of 

 agricultural education. The work was then so widely 

 appreciated that a new edition was soon called for, and 

 there can be no doubt that in its new form it will be more 

 popular than ever, for Miss Ormerod has done every- 

 thing in her power to make it not only scientifically 

 accurate but practically useful. Students will find it of 

 great service in helping them to a knowledge of insect 

 life and of the best remedies for " infestations." 



LETTERS TO THE EDITOR. 



\The Editor does not hold himself responsible for opinions ex- 

 pressed 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 of Nature. 

 jVo notice is taken of anonymous communications.'\ 



A Functional Hermaphrodite Ascidian. 



As of late years a considerable number of structural her- 

 maphrodites have been shown to be protogynous or prot- 



NO. I 198, VOL. 46] 



androus, or to have some special modification for the purpose of 

 preventing self-fertilization, it may be of interest to have on 

 record a case of a completely functional hermaphrodite. 



I had living lately in one of my dishes a large Ascidia 

 (probably A. tubictinda of Hancock) which I observed one 

 morning to be expelling eggs from the atrial aperture. The 

 eggs were emitted in batches of from about twelve to twenty at 

 a time, and immediately after each set of eggs came a little 

 white milky jet which hung like a string in the water for a few 

 seconds and then spread out and disappeared. On catching 

 some of this string in a pipette and examining it with the micro- 

 scope it was seen to be a mass of active spermatozoa. This 

 alternating passage of ova and spermatozoa continued for fully 

 an hour. 



The ova at first floated at the surface of the water for a short 

 time and then slowly sank to the bottom. On examining some 

 of those on the bottom of the dish after a couple of hours they 

 were found to have commenced development, being in various 

 stages of segmentation : so there can be no doubt that self- 

 fertilization had taken place. 



Very likely this occurs in some other species also, but another 

 common Ascidian {Corella parallelogramma), of which I had 

 had several large specimens living a tew weeks before, laid eggs 

 in my dishes, and 1 could not detect any spermatozoa being pro- 

 duced by these individuals. They were functionally female 

 although structurally hermaphrodite. 



\V. A. Herdmax. 



University Colleg e, Liverpool, October 3. 



The Present Comets. 



On the 27th ult. about i5|h. G.M.T. comet Brooks (.•, 1892) 

 had a tail 10' long, pointing at a position-angle of 280°. 



At the latter part of last month Swift's comet {a, 1892) was 

 still a very conspicuous object in a 4i-inch refractor. Obser- 

 vations on several nights showed that it not only still had a very 

 faint tail— at posiiion-angle 260" on the 24th at 8ih, when I 

 observed it to be certainly 11' long, and suspected it to 21' — but 

 that also there was an elongation nearly in the opposite direction ; 

 while I believe the radius of the head was less towards n than 

 towards s, but I have not been able to satisfy myself of this. 



Sunderland, October 5. T. W. Backhouse. 



Women and Musical Instruments. 



In looking over a very large collection of musical instruments 

 from the aborigines of America, I am surprised to find that there 

 is not one peculiar to women, and that those of the men are 

 never played by the women. It is true that the females beat 

 time on various objects and may now and then use the rattle. 

 This disappointing fact arrested my attention, and I am curious 

 to know whether savage women, or any other women for that 

 matter, have ever invented a musical instrument, and whether 

 in savagery they even play upon those invented by the men. 

 The composition and singing of songs might also be inquired 

 into, though our American savage women do join in certain 

 choruses. Oxis T. Mason. 



Washington, U.S.A., September 26. 



Determination of ^' by Means of a Tuning Fork. 



Mr. C. V. Boys informs me that for the converse process of 

 determining the pUch of a tuning-fork, the experiment I de- 

 scribed recently is no new one, but has been used by him for the 

 last ten years in the instruction of students in South Kensington. 

 I observe, however, that he has not made the same use of the 

 trace to eliminate the zero error. A. M. Worthington. 



THE TOTAL ECLIPSE OF THE SUN, 1893. 



AS I have been asked by some astronomers to give a 

 description of the general appearance and climate 

 of this part of Chile, in which a total eclipse of the sun 

 occurs next year, I have drawn up for publication the 

 following account : — 



The eclipse takes place on April 16, 1893,31 about 

 8.15 A.M., Chile local time, and will be seen to the 

 greatest advantage in this part of the Province of 

 Atacama. 



