February 17, 19 16] 



NATURE 



677 



Iy these arrangements effective instruction in the 

 jeum is provided for 900 to 1000 children per week, 

 his worlc was undertaken in response to the appeal 

 he Education Committee, and in one sense at least 

 lay be regarded as war emergency work. Its real 

 value and usefulness have already been appreciated by 

 the education authorities and by the teachers. But if 

 the museum should be closed down, how can the work 

 go on ? What is to be done with the children ? They 

 have already been deprived of their schools by the 

 military authorities. It is very desirable that they 

 should not now be denied the valuable alternative 

 instruction provided for them. The same problem 

 will probably arise in many of the provincial towns 



I the country where similar work is being done. 

 W. M. Tattersai.i.. 

 phe Manchester Museum. 



A Relation between Atomic Weights and 

 Radio-active Constants. 



interesting relation given by Mr. F. Gilbert 

 ruthers in Nature of January 20, p. 565, holds, for 



anemone Adamsia palliata. When I first noticed the 

 dead hermit-crabs both lay on the gravel at the bottom 

 I of the tank with their ventral surfaces uppermost, 

 ! and in both cases the abdomen was partially with- 

 ', drawn from the molluscan shell. Both had been 

 I attacked and partially enveloped, one by two half- 

 l_grown specimens of the asteroid Porania pulvilhis, 

 ! and the other by one rather larger specimen. 

 { As I have for some time been interested in the 

 ; feeding habits of Porania and Solaster, I wished to 

 see what would happen and did not disturb the speci- 

 ! mens until the following morning. I then found that 

 I no appreciable impression had been made by the star- 

 fishes upon the soft abdomens of the hermit-crabs ; 

 but I was much interested to find that in both cases 

 the enveloping anemone had discharged a consider- 

 able number of acontia, with which the actinal sur- 

 faces of the starfishes, and probably their partially 

 i everted stomachs, had been in contact. 

 '• My observations of the feeding habits of Porania 

 have extended over two years, and I have invariably 

 found it an exceedingly slow feeder. As shown by 

 , Gemmlll (Proc. Zool. Soc, March, 1915, p. 13), this 

 species is capable of subsisting for long periods upon 



microscopic food particles 



swept into the digestive 

 tract by ciliary currents. 

 My own observations tend 

 to confirm those of Gemmill ; 

 and in view of such a capa- 

 city it appears to me to be 

 remarkable that a voluntary 

 attack should have been 

 made upon so large a morsel 

 as the abdomen of a Eupa- 

 gurus, especially when pro- 

 tected, as is commonly 

 assumed, by an actinian. 

 The anemones did not show- 

 any outward sign of injury 

 beyond partial relaxation of 

 their hold upon the 

 molluscan shells. 



H. C. Chadwick. 

 The Biological Station, 

 Port Erin. 



Colourless Crystals of 

 Hsemo^'lobin. 



Log Atw. 2-33 



2-34 



2-35 



2-36 



corresponding isotopes, nearly exactly, if, as suggested 

 by Fajans, the atomic weight of actinium should be 

 227 instead of 226. From IV. to VLB the only excep- 

 tion is AcX (and perhaps Ra). But the lines are not 

 parallel, and not equally spaced. 



A. VAN nr\ Broek. 

 Gorsel, Holland, January 25. 



Asteroids Feeding upon Living Sea-Anemones. 



As bearing upon the observations recorded by Mr. 

 H. N. Milligan in Nature of February 3, I should 

 like to say that two of ten specimens of Eupargurtis 

 prideauxii, which have been kept in the aquarium of 

 this institution since last autumn, died on January 23. 

 The molluscan shell occupied by one of these speci- 

 inens was that of Trochus magus, that occupied by 

 the other was of Scaphander lignarius. Both shells 

 were, as usual, enveloped by a specimen of the 



NO. 2416, VOL. 96] 



Crystals of haematoidin 

 in old blood extravasations 

 in tissues are not — or at 

 any rate have not been in 

 the cases I have examined — soluble in chloroform or 

 other solvents of bilirubin either with or without 

 acidification. The colour dissolves out readily enough, 

 but a transparent shape remains in the form of the 

 original crystal. I have assumed that this remnant is 

 a proteid basis similar to those which are well known 

 in the crystals of urinary deposits and in calculi, and 

 it is possible that Prof. Fraser Harris's curious experi- 

 ences with haemoglobin crystals are explicable along 

 these lines. It is at least likely that haemoglobin 

 crystals prepared in the ordinary way contain also 

 some serum proteid. A. E. Boycott. 



17 Loom Lane, Radlett, February 4. 



Tubular Rock Structures. 



The council of the Geophysics Society desires to 

 i obtain records of mineral growths taking the form of 

 ! hollow cylinders — those not due to organisms, and 



