NOTES AND MEMORANDA. 187 



surface of the sponge, and clothing the canals is devoid of 

 cilia, which are present only in the ciliated chambers. The 

 species diifers also in other histological details from H. lohu- 

 laris, such as in possessing branched connective tissue fibres 

 in the mesoderm like those of Medusee ; the mode of commu- 

 nication between the inhalent and exhalent canal systems is 

 also different, and takes place by means of irregularly sac- 

 shaped or even sometimes somewhat branched ciliated cham- 

 bers. 



Schulze has also described in the last number of the 

 ' Archiv fiir Mikrosk. Anat.' a new hydroid polyp which 

 lives invested by sponge-colonies. He terms it Spongicola. 

 It is to this parasite or a similar form as suggested by 

 Carter, that Elmer's observation of thread cells in sponges 

 (Renieridse) is due. Prof. Allman has described in ' Nature,' 

 July 30th, 1874, a hydroid of similar habit under the name 

 of Stephanoscyphus. 



On the Structure of Striped Muscle-Fibres. By Cand.Med. 

 WiLHELM BiEDERMANN, from the Physiological Institute at 

 Prague (' Vienna Sitzungsberichte d. k. Akad.,' Juli, 1876). 

 — The interstitial substance between the primitive muscle- 

 fibrils, discovered by KoUiker, has by some recent histologists 

 — Sachs, R. Arndt, and especially J. Gerlach — been regarded 

 as intimately connected with the intramuscular nerve-ter- 

 minations. Arndt regards each individual fibril as contin- 

 uous with the nerve of its bundle, /. e. the so-called muscle- 

 column (KoUiker), and J. Gerlach asserts that the isotropous 

 substance of a muscle-fibre is directly connected with the 

 intramuscular nerve. Gerlach arrived at this conclusion from 

 the study of muscle-fibres treated with gold solution. Under 

 this reagent there appear within the muscle-fibre granular or 

 rod-like structures arranged in a more or less distinctly linear 

 manner (Spenkelung) so as to resemble at some places fila- 

 mentous structures of a varicose appearance quite like 

 primitive nerve-fibrils that had been stained with gold 

 solution. 



Biedermann in the above paper shows that that dotted 

 appearance (Spenkelung) can be invariably produced by 

 staining muscle-fibres of Crustacea, insects, or vertebrata, 

 while they still possess the power of contracting, in 1 per 

 cent, solution of chloride of gold. The fibres are placed in this 

 solution for five to ten minutes, having been previously kept 

 in a somewhat dilute formic acid ; they are then brought into a 

 watchglass of water and a few (one or two) drops of formic acid, 

 where they are kept for twenty-four hours in a dark place. 



VOL. XVII. NEW SER. N 



