Chapter VII.— THE TEGUMENTAL GLANDS. 
The shell of the lobster, as has been seen already (pp. 77, 78), is not a solid armor, 
biit 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 setoe 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, subsplierical 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 Vo mm - (cuts 4 and 5, pi. A, and fig. 208, pi. 49) and its diameter only -,4=- 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.” 
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 pi aces 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. Rarely 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 in 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 Patten and W atase for valuable suggestions. 
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