Prof. E. Claparede on the Structure of the Annelida. 345 



and cellular [corium, Ratlike, derme, Quatref.), corresponding 

 with the subcuticular or chitinogenous layer of the other Arti- 

 culata ; the other extra-cellular, the cuticle [epidermis, Rathke 

 & Quatref.), sometimes very delicate, sometimes composed of a 

 thick layer of chitine. The integuments have hitherto been 

 studied with care only by M. KoUiker, to whom we are also 

 indebted for several other excellent works on the histology of 

 the Annelida, works all of which have unfortunately remained 

 unknown to the author of the ' Histoire Naturclle des Anneles/ 

 The superficial layer deserves the name which has been given 

 to it by M. Kolliker. From a histogenetic point of view it falls 

 perfectly under the category of cuticular fomnations. The sub- 

 cuticular layer {liypodermis, Weism.) which secretes it may often 

 be denominated, as it is by M. Kolliker, an epithelium ; however, 

 in most cases it is impossible to recognize the limits of its con- 

 stituent cells. The nuclei seem rather to be scattered iu it with 

 considerable regularity in a continuous granular stratum, as has 

 been seen by M. Baur in certain Arthropoda. Wherever the 

 cuticle attains a certain thickness, it presents two systems of 

 strife at right angles (or more frequently about 70°), which have 

 been already well observed by M. Kolliker*. The tubular pox'cs 

 [Porenkundle of the Germans), when they exist, are distributed 

 in lines congruent with these striaj. M. Kolliker has been 

 struck by the distance which separates these pores from each 

 other. Frequently, he says, not more than one of them corre- 

 sponds with each subjacent cell; and he asks whether these 

 apertures are really the homologues of the tubular pores [Puren- 

 kaidlle) of the Arthropoda, or whether they may not rather be 

 compared with apertures of the cutaneous glands, such as those 

 discovered by M. Leydig in the Piscicolce, or with the hairs of 

 Insects and Crustacea. To this question I can reply positively 

 that the two categories of pores exist in the Annelida. Those 

 which serve for the discharge of certain secretions seem to exist 

 in all species. Sometimes, especially in the large species, they 

 attain a considerable diameter ; but usually they are very wide 

 apart. Sometimes, however, we find them brought together in 

 groups or islets. The canalicular pores are much smaller and 

 much closer together, and do not correspond with glands. They 

 occur only in the species with a thick cuticle, and not even in 

 all these. 1 shall describe some examples in detail, especially 

 among the Euaicea. Wherever these very fine and approximated 



* M. de Quatrefages, to whom these striae are not unknown, sees in them 

 the indication of two systems of fibres — an opinion which may be provi- 

 sionally admissil)le in the case of certain worms. In any case the learned 

 Academician with justice attributes to these striae the iridisation of the 

 surface of the body in many Annelides. 



