iS6 



NA TURE 



[June 22, 1905 



and by mutual pressure produce a distortion of the 

 normally circular base. There can be no doubt that in 

 this coral, as in others investigated by Dr. Duerden, these 

 clusters of larvre become organically connected, and form 

 aggregated colonies. 



In dealing with the later stages of the development, the 

 author discusses many questions of great interest to those 

 who have made a special study of the anatomy of corals. 

 We may refer especially to the light thrown upon the 

 vexed question of " tlieca " and " epitheca," to the 

 demonstration that the primary ectosepta do not become 

 entosepta as they were supposed to do in some other 

 corals, and to the valuable suggestion as to the scientific 

 method of writing the septal formulse of corals. These 

 and other matters, which are fully discussed, render the 

 memoir of greater value than a mere record of facts and 

 observations of the natural history of a single species of 

 coral would be. There is a great deal to be said in favour 

 of the old type system, the system of presenting to the 

 reader a plain, unvarnished tale of the natural history of 

 a species and leaving him to draw his own conclusions ; 

 but the dangers of the system may be clearly recognised 



Wl '% 



measured rate, and the products of combustion are cooled 

 down by a stream of w'ater also flowing at a known rate, 

 the ingoing and outgoing temperatures of which can be 

 accurately measured. In spite of the difliculties of securing 

 accurate measurements of the rate of flow of gas and 

 water, on account of the speed with which consecutive 

 determinations can be carried out instruments of this type 

 are mostly used by gas engineers. Their chief defect is 

 want of portability, and as an alternative a sample of the 

 gas is frequently analysed, and the calorific value deduced 

 from the results of the analysis. Apart from the difficulty 

 of exactly determining the constituents of such a com- 

 plicated mixture as coal gas, this method implies that the 

 exact calorific value of each substance present is accurately 

 known, and this, unfortunately, is far from being the 

 case. 



Most of the data regarding heats of combustion in actual 

 use are derived either from the experiments of Berthelot and 

 his pupils with the calorimetric bomb, or from the experi- 

 ments of Julius Thomsen, and in the case of gaseous sub- 

 stances tlie differences between these two experimenters 

 may amount to as much as 2 per cent. In the current 

 number of the Zcitschrift fur physikalische Chemie Julius 

 Thomsen has a critical paper on the causes of these differ- 

 ences, and comes to the conclusion that for gases the 

 explosion with compressed oxygen in a bomb gives quite 

 untrustworthy results. His chief argument is based on the 

 comparison of the values obtained for the heats of com- 

 bustion of homologous series of hydrocarbons and their 

 halogen derivatives, and it is shown that whereas the 

 method of combustion at ordinary atmospheric pressure 

 gives remarkably constant differences between the con- 

 secutive members of such a series, the results obtained by 

 means of the calorimetric bomb lead to differences between 

 consecutive members which are quite irregular. It follows 

 that the values obtained for heats of formation, which lie 

 at the basis of all theoretical speculations in this field, are 

 still more irregular in the case of figures obtained with 

 the bomb, since they are based on the differences between 

 the heats of combustion. The weak point in most physical 

 work on gases is usually on the chemical side, and on 

 account of the extreme practical and theoretical importance 

 of the subject and the great advances made in the last ten 

 years in the methods of preparation of pure gases, there 

 is still room for a re-determination of these constants. In 

 this connection it may be pointed out that the ultimate 

 mode of calibration of gas calorimeters of the Junker type 

 is the combustion of a known quantity of a pure gas the 

 heat of combustion of which is taken as known. 



G. N. H. 



in this memoir. The ccral under review is a common, and 

 many might think a common-place, coral, and if the 

 author had thought fit to limit himself to a description 

 of facts only, it would probably have been chosen as a 

 type of its order by writers of the conventional text-book. 

 Fortunately, however, we are warned on almost every page 

 that Siderastrasa is not a type, but in many respects an 

 e.'cceptional and rather archaic form. 



In conclusion, a word of praise must be said for the 

 manner in which the memoir is presented to the public. 

 Like the other scientific treatises that have been recently 

 published by the Carnegie Institution at Washington, the 

 paper, printing, and illustrations are all of first-rate 

 quality- S. J. H. 



G.45 CALORIMETRY. 

 TN the recent report of the Departmental Committee 

 appointed to consider the question of the control of 

 the gas supply of the metropolis, a proposal was made that 

 the calorific power of the gas should be regularly deter- 

 mined, thus recognising the growing importance' of the 

 heating value of gas as distinguished from its illuminating 

 power. The use of gaseous fuel both for heating and 

 power purposes having led to a demand for exact gas 

 calorimetry, several types of calorimeter have come into 

 use. In those of the Junker type, the gas is burned at a 

 NO. i860, VOL. 72] 



UNIVERSITY AND EDUCATIONAL 

 INTELLIGENCE. 



Oxford. — The following is the text of the speech de- 

 livered by Prof. Love in presenting Prof. E. Ray Lankester 

 for the degree of D.Sc. honoris causa on June 13 : — 



Salutat Academia nostra Edwinum Ray Lankester, 

 alumnum suum. Hie ille est, cuius magna apud nos est 

 memoria Anatomic Comparative cathedram olim tenentis, 

 quod et discipulis ardorem suum miro modo inspirare 

 potuit, et specimina in usum Mussel nostri diligentissime 

 congesta ita novis rationibus coUocavit ut Historise 

 Naturalis principia luce clariore illustraret ; qui banc 

 Academiam ut suos mores emendaret toties hortatus est, 

 quae ad inauditam perfectionem iamdudum pervenisset si 

 monitori amicissimo in Actis Diurnis contionanti obtem- 

 perare voluisset. Hie est cuius ex repertis laudis aliquid 

 ad suam Almam Matrem redundavit, cum inter insig- 

 nissimos doctores qui hodie de animalium figuris disputant 

 fere princeps sit et in omnibus virorum doctorum 

 societatibus summo in honore habeatur. 



Nihil profecto quod ad Anatomiam Comparativam 

 pertinet non in huius viri scientiam cadere videtur. Neque 

 enim huic satis erat edendi curam suscipere cum Acta ilia, 

 quae summ.-E auctoritatis in hoc genere apud nos sunt, 

 labore per quinque et triginta annos iam continuato, turn 

 luculentissimorum librorum seriem, e quibus plures iam 

 typis impress! in manibus omnium habentur, quod onus 



