FUNCTION OF THE CALCAREOUS BODIES. 283 



calcium salts) in the case of a newly examined Tcenia marginata, 

 according to an analysis made at my request by Professor Naumann 

 in Giessen. But the most superficial micro-chemical examination 

 reveals in the calcareous bodies the presence of an organic mass whicl 

 is associated with the lime, and which can even be isolated as a clear 

 ball of the original size by dissolving out the lime with an acid. Since 

 this process is accompanied with more or less effervescence, the lime 

 is therefore, for the most part, though we cannot say exclusively, 

 deposited as carbonate of lime. 



In some cases the bodies do not effervesce on being treated with 

 acid, and this even in some species where they have previously been 

 observed to do so. I tried formerly to explain this fact by the suppo- 

 sition that the carbonate had been replaced by some other salt of lime, 

 but I have been informed by Sommer and Landois that small quantities 

 of carbonic acid gas, instead of escaping in bubbles, are absorbed in 

 statu nascente by the surrounding fluid, and that thus the absence of 

 effervescence is in no way a sign of a complete absence of carbonic 

 acid gas. 



That effervescence should be absent when the calcareous bodies 

 are present in smaller numbers, seems to me hardly to explain why it 

 should be absent under certain circumstances in forms which usually 

 exhibit it. Nor is the development of gas observed in all the cor- 

 puscles in equal intensity. Since they also differ markedly in appear- 

 ance, lustre, and power of refracting light, I think we may assume 

 that not only the number, but the composition of these calcareous 

 bodies, is subject to manifold individual and specific variations. 



It appears to me a mistake to regard the calcareous bodies of the 

 Cestodes as unalterable and permanent structures. As they arise and 

 increase during the development of the joints, so they under some 

 circumstances decay. This is most, easily observed in species where 

 they are numerous. Thus Tcenia serrata is not only much more richly 

 provided with them in its cysticercoid stage than later, but it at first 

 possesses them abundantly in the middle layer of the proglottides, 

 where they afterwards often almost wholly vanish in the more mature 

 stages. We are irresistibly reminded of the history of the so-called 

 " crab-stones," which are known to represent reserve materials ; and 

 we are well aware of various epochs .in the life -history of Cestodes 

 when there is a temporary demand for a large quantity of lime, and 

 especially of carbonate of lime, e.g., to neutralise the acid digestive 

 juices, and to form and harden the egg-shells. 



Phosphoric, carbonic, hydrochloric, and sulphuric acids have also been detected. The ashes 

 yielded a smaller quantity only 4'9 per cent. but this was in the case of a specimen 

 of Tcenia solium which had been kept for long in spirits. 



