104 Mr. W. Percy Sladen on the 



paration to place the pedicellarise, immediately after removal 

 from the test, in alcohol of 70 per cent, acidulated with 

 2 per cent, of HC1 ; and then, when decalcification has been 

 effected and all traces of the acid thoroughly removed by 

 repeated washings, to stain in hematoxylin. 



A transverse section through the stem- dilatation (PL XII. 

 fig. 8) presents the following series of tissues : — 



1. Epithelial nucleated cells of the investing membrane ; 

 2. A neuro-muscular layer with granular fusiform cells dis- 

 tributed here and there ; 3. Tissue with numerous large 

 colourless cells; 4. A layer of large areolar spaces and 

 gland-cells and ducts ; 5. The central mass, composed of a 

 very finely reticulated substance, densely filled up with mucous 

 matter (PL XII. fig. 8). A longitudinal section through the 

 organ indicates the distribution of these tissues, and also that 

 the structure enumerated above belongs essentially to the 

 gland-sac, with the exception of the epithelial layer of the 

 common investing membrane. 



In the longitudinal section of the stem neuro-muscular 

 bands may be seen traversing its length, and bead-like bands 

 of granular fusiform bodies, connected at the extremities by 

 delicate fibres, immediately underlying the cuticular epithe- 

 lium. Although I was at first sight disposed to regard 

 these as simple pigment masses, I am now inclined to con- 

 sider them more intimately connected with nerve-structure. 

 That they are different from the true pigment masses will 

 be seen on examining a specimen from which the colour has 

 not been discharged — the cells of these latter being much less 

 regular in shape and much more numerous, and not united 

 into the same longitudinal bead-like bands by the delicate 

 fibres referred to above. 



The calcareous shaft occupies only a small space in the 

 centre of the stem, and is surrounded by a considerable thick- 

 ness of nucleated connective tissue. The granular (nerve ?) 

 cells are found to be densely crowded immediately above the 

 glandular sacculi. The foramen of the sacculus is surrounded 

 by a strong sphincter muscle. The whole investing mem- 

 brane of the pedicellaria globifera (head, stem, and saccular 

 dilatation alike) is indurated on its outer surface with a large 

 number of small, curved, calcareous spicules somewhat re- 

 sembling the letter C in form, and having a slightly thickened 

 or rounded knob-like termination at each extremity. 



It occasionally happens that a pedicellaria globifera may 

 be met with which is devoid of the glandular sacculi upon its 

 Stem j and no difference would at first sight be noticed between 



