5] 2 Miscellaneous, 



the angles wore roun'ied off. Ludwig found the glands in very 

 large numbers, upon the disk as well as upon the arms, extending 

 close up to the ambulacral grooves, and in general situate upon the 

 area of the body supported by the skeletal plates ; he failed to find 

 them in the central portion of the pore-fields, between the papulte. 

 Ludwig adds that the same glands also occur in other species of 

 Echinaster (e. (/. in Echinaster callosus SiXid Crihrella ocalata). Witb 

 reference to the finer structure of the glands, Ludwig refers to 

 Cuenot's paper, " Contribution a I'etude anatomique des Asterides " 

 (Arch. Zool. expe'r. [2] t. obis, 1888, pp. 11-13, pi. i. figs. 15-17). 

 In the sections that he made of Echinaster sepo.<itus Cuenot found 

 that the glands were of irregular shape, 0-~) mm. in length, more or 

 less spherical, enveloped by the fibrillar layer beneath the epithelium 

 of the body; the aperture appeared as a shallow depression. Cuenot 

 further states that in the gland there are meshes of connective 

 tissue, surrounding oval spaces, and that in each mesh there lies 

 a large cell, which forms the vesicles that are found in the cell and 

 in the ejected mucus. 



I studied the glands in very small specimens of Ecli'mastcr srposifas 

 which Herr Geheimrath Ludwig most kindly gave me and in larger 

 animals which I had preserved at Naples ; besides these I also 

 made use of CribrdUa ocalata { — sxnguinolenta) from the Plymouth 

 Biological Laboratory. 



In young animals the origin of the glands at the tips of the arms 

 can be clearly seen. They are formed by means of the invagination 

 of the epithelium of the body ; the primitive gland is a wide open 

 invagination ; the neck gradually becomes narrower and the gland 

 assumes the typical form. The cells of the external epithelium 

 which have thus sunk inwards multiply grcatlv and lose their regular 

 arrangement : the new cells become detached and are pressed into 

 the lumen of the gland ; in the case of Echitmster sepositus the)' are 

 some 11 to 15 /^ in size, and in that of Cribrella oculata about 13 

 to 19 jji, generally not quite round, but somewhat elongate ; the 

 roundish nuclei of these cells measure approximately 2 i_i. Between 

 the parietal cells and those that are free only a slight difference in 

 shape is perceptible ; here and there among the fixed cells are to 

 be found some that are in process of division. By the bursting of 

 the free cells the mucus is poured into the gland ; the small nuclei 

 are mingled with it. The glands are surrounded by strong fibres of 

 connective tissue, but nowhere is any connective tissue to be found 

 in the interior of the gland. 



If a starfish of this kind is irritated and the skin contracts, the 

 mucus exudes from the affected spot in small droplets, and investi- 

 gators are unanimously of the opinion that these glands of the 

 species of Echin^ister serve as organs of defence. — Z)olo;jischer 

 Anzeifjcr, Bd. xxix, Xo. 20 (Jan. 8, 1906), pp. 639-640. 



I 



