Chapter VII.— THE TEGUMENTAL GLANDS. 



The shell of the lobster, as lias been seeu already (pp. 77, 78), is not a solid armor, 

 but is everywhere perforated by capillary canals which open by minute pores at the 

 surface. One set of these ducts is called the hair pores. These lie immediately 

 beneath the hairs or setai of the shell. The other set constitutes the ducts of the 

 tegumental glands. 1 



The tegumental glands are very generally found in the decapod Crustacea, and 

 they are more widely distributed over the body of the individual than almost any 

 other organ. Nevertheless their structure has never been accurately determined, and 

 almost nothing is known of their function. They lie in the dermis or in the connective 

 tissue and adjoining muscles immediately below the cuticular epithelium. They are 

 opaque, subspherical or oblong, not usually over | mm. in longest diameter, and 

 each communicates with the exterior by means of a capillary duct, the entire length 

 of which — not including the part which traverses the cuticle — is probably not more 

 than y 1 ,, mm. (cuts 4 and 5, pi. A, and fig. 208, pi. 49) and its diameter only ji s mm. 

 These minute organs are scattered all over the body and appendages; they are 

 particularly abundant about the mouth and in the oesophagus, and Vitzou has found 

 them in the walls of the intestine of Palinurus (197). As he remarks, "one may 

 study these organs indifferently in a macruran or brachyuran, for they have the same 

 structure in both. 1 ' 



GENERAL STRUCTURE OF THE TEGUMENTAL GLAND. 



The tegumental gland, wherever found, whether in the appendages or beneath the 

 skin of the body proper, has the structure shown in cut 5. It consists of a central 

 reticulate body or rosette, the exact nature of which is unknown. In the midst 

 of this there is a small cavity, which is continued into a short capillary duct. The 

 latter perforates the cuticle and thus places the organ in direct communication 

 with the exterior. Grouped about the rosette is a cluster of gland cells of various 

 shapes and sizes. Each has a broad base and tapering central end, which is united to a 

 process of the rosette. Each organ is supplied with a nerve and contains an eccen- 

 tric, bipolar cell, which resembles a ganglionic cell. One of the processes of the 

 latter joins the rosette, while the other unites with the nerve. Barely two such cells 

 appear in the same organ. The duct and nerve usually issue from the gland together, 

 the former possessing apparently, for at least a part of its course, a thin sheath. 

 Each organ is usually surrounded with a delicate capsule, probably of connective 

 tissue, though it is not always possible to detect such an envelope. 



I have .seen no branching of ducts, each organ opening independently at the 

 surface, and I have not succeeded iu determining with any degree of satisfaction the 

 relation which the nerve fibers bear to the gland cells. 



1 Similar structures have been called dermal glands, salivary glands, and cement glands. While it is 

 probable that they originate in the epidermis, it may be better to classify them under the generic 

 term of tegumental glands. 



In the work of this chapter, relating to histology and technique, I wish to acknowledge my 



indebtedness to Professors Patteu and Watase for valuable suggestions. 



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