154' Prof. M. Schultze on Hyalonema. 



The main argument of my colleague Dr. Gray is evidently 

 the apparently constant union of a polype with the Hyalonema j 

 in such a manner that the polype covers a greater or less portion 

 of the " Glass Rope ^' like a bark, and stands in the same relation 

 to it as the polypes of Gorgonia to the solid axis. In the dry 

 specimens in our collections the polype-bark generally adheres 

 very firmly and closely to the siliceous threads, so that nothing 

 can appear more natural than that the polype formed the threads, 

 or, in other words, that the " Glass Rope '' represents the solid 

 axis of the polype-tube. I will lay no stress upon the fact 

 that in nearly all the specimens which I have seen in Leyden, 

 London, Paris, and Berlin, and also in those in my own posses- 

 sion, the total number of which, including those figured by 

 Brandt, is at least fifty, the polype forms only an imperfect coat 

 upon the " Glass Rope,'' because it is evident that, in some of 

 these specimens, a part of the polype-coat has been removed ar- 

 tificially or by accidental injury. Nor will I attach any impor- 

 tance to the circumstance that hitherto no other polype is known 

 the axis of which consists, as in Hyalonema^ of loosely united long 

 threads, the incombustible constituent of which is formed almost 

 exclusively of silicaj whilst as yet only lime salts are known in 

 the skeletons of polypes. For, as Dr. Gray indicates, why should 

 not an exception to the rule occur? Moreover I may add, 

 might not the allied forms have disappeared during an earlier 

 geological period ? So far, therefore, we have evidently nothing 

 essential to oppose to Dr. Gray's opinion. 



On the contrary, a very decisive significance belongs to the 

 following point, to which I have already called attention in 

 my monograph, and which, I regret, has been passed over in 

 silence by Dr. Gray. On microscopic examination the long 

 threads of the "Glass Rope" show a structure which is per- 

 fectly characteristic of sponge-spicules. To all acquainted with 

 the subject it is sufficient to state that the threads possess a 

 regular, fine, concentric stratification and contain a fine central 

 canal in their axis, exactly such as distinguish the sponge-spi- 

 cules from all other natural products and exclude all confusion 

 with other skeletal structures of lower or higher organisms. As 

 a witness in favour of my view, I may here cite the most ex- 

 perienced of living micrographers, Ehrenberg, who never doubted 

 for a moment that the long siliceous threads were sponge-spi- 

 cules. Dr. Bowerbank also, the celebrated student of Sponges, 

 immediately recognized the threads of Hyalonema as sponge- 

 spicules. Here no escape is possible, the microscope decides 

 inexorably : the siliceous threads are sponge-spicules ; and 

 therefore a polype cannot have formed them. If, notwith- 

 standing, they are coated by a polype, this must be a parasite. 



