666 PROF. MIXCHIN AND DR. REID ON THE [June 16, 



sponge-spicules, and especially with respect to the amount of 

 organic mattei^ present in them. While Haeckel, Lendenfeld, 

 Maas, and Weinschenk assert or assume the presence of con- 

 siderable quantities of organic substance in the spicules, Kolliker 

 and Ebner allow none at all except in the sheath, and Biitschli 

 admits the existence only of a trace of organic matter and 

 considers even the sheath to be largely inorganic. It should be 

 further pointed out that the two most detailed investigations, 

 upon this question, namely, those of Ebner and Biitschli, were 

 based, so far as the composition of the spicules is concerned, on a 

 very limited number of forms ; Biitschli, in fact, studied only the 

 large monaxons of Leucandra aspera. Hence there is a possibility 

 that their investigations do not cover the whole range of varia- 

 tion that those spicules may present. Both Ebner and Biitschli 

 worked at the largest types of spicule that they could obtain, in 

 order to facilitate the handling and treatment of the material. 



Observations upon Calcareous Sponge-spicules. 



Our investigations have been directed towards endeavouring to 

 demonstrate the existence of a residue after decalcification, by 

 means of specific stains, as Ebner attempted to do, but without 

 success. It is obvious that if any organic residue were left after 

 decalcification, it might be expected to have an afiinity for certain 

 stains and not for others, and might therefore be demonstrable 

 only by means of particular dyes, so that the negative results 

 obtained by Ebner would not necessaiily disprove the existence 

 of an organic residue. We obtained in all cases positive results- 

 with nigrosin, as stated previously by one of us (Minchin, 1898), 

 and also with the allied stain indulin. In our investigation we 

 have made use chiefly of the spicules of C'lathrina contorta, but 

 we have examined the spicules of several other species : of Olath- 

 rinidse, Clathrina clathrus and Ascandra falcata ; of Leuco- 

 soleniidse, Leucosolenia lieherkiihnii and L. complicata ; and of 

 Heterocoela, Sycon ciliatum, Leticandra aspera^ and Heteropegma 

 nodns-gordii. 



Our method of procedure was as follows. A piece of the 

 sponge taken from a specimen preserved in alcohol was washed in 

 water and placed in a tube of a small hand-centrifuge with a few 

 drops of Eau-de-Javelle, and gently shaken. In a short time, 

 generally about half-a-minute, the sponge is dissolved into a 

 cloud of spicules. The tube is then filled up with distilled water 

 and shaken up, and then with the centiifuge the spicules are 

 driven down to the bottom of the tube. The liquid is then 

 carefully poured ofi", taking care not to disturb the spicules, the 

 tube is filled up again with water, shaken up, and the process 

 repeated. In this way the spicules can be given three or four 

 washings in as many minutes, and are freed both from organic 

 matter of the sponge-body and from the Eau-de-Javelle. The 

 next procedure was usually to add to the tube containing the 



