Dr. J. E. Gray on the Growth of Hyalonema. 193 



of the British Islands" (Proc. Koy. Soc. xvii.), he seems to 

 have male the same mistake: thus at page 176 he states, "As 

 it thus appears that these siliceous sponges, when growing on 

 the surface of the mud, send root-fibres (so to speak) far and 

 wide into its substance, the idea previously suggested by Prof. 

 Loven, that the elongated flint-rope of Hyalonema Sieboldii is 

 in reality the mud-imbedded stem, supporting the sponge with 

 which it is connected, instead of being implanted in the sponge 

 and supported by it (which is the commonly received opinion) , 

 seems the more likely." 



Prof. Loven has made this distinction himself very plainly 

 in a very amusing and instructive letter, which he most kindly 

 sent to me immediately on the publication of my paper in the 

 1 Annals :' — 



" I have just read your paper in the Ann. & Mag. 4th ser. 

 No. 10 ; and, as I am not very fond of differing from you, 

 I am glad to find that you now turn the old Hyalonema 

 upside down — that is, place it with ' the sponge ' upwards. 

 This view, I see, is confirmed by Prof. Perceval Wright, who 

 says, just as I maintained, that the ' siliceous axis ' is the stem 

 of the sponge ; and also by Prof. Wy ville Thomson, who 

 found the Hyalonema growing upside down, which he might 

 have more than ' suspected ' from my paper. So far we all 

 agree. As to what is now the lower end (formerly the upper) 

 of the stem (coil) , you are inclined to believe it to be ' sunk 

 in the mud.' I cannot conceal that this mode of growing 

 would be very unnatural indeed, unless you at the same time 

 suppose the basal end to be provided with roots, in which case 

 you have my Hyalonema complete. 



" In order to settle the whole question, the best measure 

 would be this : let orders be given to all the ships of your 

 navy stationed in the Japan seas to dredge on the fishing- 

 grounds off Inosima, and not to give up working till they 

 have got entire specimens of the Hyalonema, with roots and 

 all (every one to be preserved in strong spirits), and in a 

 number sufficient for the glory of the British Museum *. 

 Among the contents of the dredge brought from the bottom, 

 and of which not a particle is to be thrown away, there will 

 be found, besides those entire specimens, in some of which the 

 stem will have an extraordinary length, other specimens muti- 

 lated by the dredge or by fishermen's nets, some being the 

 stumps of the basal parts with the roots, others the upper parts 

 of the stem with the head or without the same, it having been 



* Allow me to suggest that perhaps one more specimen ought to be 

 taken. 



