6 Dr. R. Greeff on the Annelid Genus Sphrevodorum, 



phery, corresponding with the nai'rowest border of the orifice, 

 breaks through, and the two ends then separate from each 

 other j so that instead of the round hole in the nuclear sub- 

 stance we have a deep indentation of the nuclear substance 

 penetrating from the circumference towards the middle. By 

 this simple process therefore, as may be readily seen, the form 

 of the above-mentioned glandular tube is very soon produced : 

 at first, by the two ends becoming rounded, it has nearly the 

 appearance of a sausage with two surfaces in apposition ; and it 

 frequently retains this form even in the fully developed state. 

 But generally, during the further growth of the tube^ its two 

 extremities separate more or less, and then one of them becomes 

 bent or rolled up, so as even to embrace the neighbouring 

 tubes; and thus the position and form of the individual glands 

 is altered in many ways, and the above-described appearance of 

 the vermiform, tortuous, glandular coil as the contents of the 

 capsule is produced. 



As regards the further histological differentiation of the indi- 

 vidual glandular tubes, these, during the processes just de- 

 scribed, become more and more filled with darkly granular 

 substance, in which afterwards larger pale bodies make their 

 appearance; these gradu.ally increase, until finally the whole 

 tube is filled with the roundish corpuscles, or, as Kolliker calls 

 them, cell-like structures, above described. The pei'fectly formed 

 glandular tube is attached by one end, or frequently, as it seemed 

 to me, by both ends_, to the wall of the capsule ; but only one 

 extremity, and with it the wall of the capsule at the same spot, 

 exhibits a roundish external orifice. 



The number of glands enclosed in a capsule is not constant. 

 The above-mentioned large capsules standing in regular trans- 

 verse rows generally contain three or four, rarely more (figs. 10 

 to 14) ; the smaller only one, or, at the utmost, two tubes. 



On various parts of the surface of the body, partly upon and 

 partly between the vesicles, and sometimes even within them, 

 we frequently see dark-brown marks [plaques), forming the most 

 multifarious figures, which are often, in consequence of their 

 tenacious consistence, much elongated, and only connected by 

 narrow bridges. These substances appear to have nothing to do 

 with the pigment-structures which so frequently occur in the 

 skin of Annelids; but whether they are, as I suppose, to be 

 regarded as the secretion furnished by the glands, and what 

 purpose is served by it in this case, I cannot decide. 



I have already called attention to the gradual transition from 

 the small clavate cutaneous structures, resembling the tentacles 

 which stand upon the anterior portion of the head, to the globular 

 ones which succeed them, and indicated that a change of func 



