150 



HARDWICKE'S SCIENCE-GOSSIP, 



according to Berkeley, but in Cheshire the name 

 given to the Agariais personaius is strangely like 

 blue-hats, a not inapt title, for it is supposed to be 

 either a fairy's hat or parasol : 



The lovely flowers of Scotland 



All others that excel ; 

 The thistle's purple bonnet, 



And the bonny heather-bell. 

 Oh, they're the flowers of Scotland 



All others that excel ; 

 For the thistle in her bonnet blue 



Still nods out o'er the fell. 

 And dares the proudest foenian 



To tread the heather-bell." 



Another confusion exists in the use of the word 

 Tetter, as applied to the white bryony ; it is tetter 

 berries, used in the skin disease known as tetters ; 

 whilst the tetter wort is the Chelidonmm tnnjiis. In 

 Ray's time, the latter term had become obsolete, but, 

 according to Halliwell, it is now commonly used for 

 the greater celandine. 



When St. Bernard founded his abbey, near 

 Clairvaux, he and his thirteen companions lived on 

 barley, or cockle-bread, with boiled beech leaves as 

 vegetables, while they were employed grubbing up 

 the forest, and in building huts for their habitation. 

 Was the cockle, so distinguished, the corn-cockle 

 now so much dreaded as a farmer's pest ? We have 

 heard the word cockle applied to the garden Nigella ; 

 this could not evidently be the plant intended, it 

 must be the Lych?iis giihago, whose seeds ha\-e some- 

 what a resemblance to cockles. 



James F. Robinson. 

 Frodskatn. 



THE ALIMENTARY CANAL OF THE 

 COCKROACH.* 



By Professor L. C. Miall and Alfred 

 Denny. 



'"PHE alimentary canal of the cockroach measures 

 -L about 2| inches in length, and is therefore 

 about 2| times the length of the body. In 

 herbivorous insects the relative length of the alimen- 

 tary canal may be much greater than this ; it is five 

 times the length of the body in Hydrophilus. Parts 

 of the canal are specialised for different digestive 

 offices, and their order and relative size are given in 

 the following table : — 



OSsophagus and crop 



Gizzard 



Chylific stomach 



Small intestine . 



Colon . 



Rectum 



• 95 in. 



.1 



•5 



■375 

 •25 



2-775 



The principal appendages of the alimentar>- canal 



<,n^"'' o,'^^'= Natural History of the Cockroach," and the 

 ^'^f S'<e'eton of the Cockroach," see this journal, March 

 ana May, 1884. 



are the salivary glands, the caecal diverticula of the 

 stomach, and the malpighian tubules. ^ 



Considered with respect to its mode of formation, 

 the alimentary canal of all but the very simplest 

 animals falls into three sections, viz., (i) the 

 mesenteron, or primitive digestive cavity, lined by 

 hypoblast ; (2) the stomodseum, or mouth-section, 

 lined by epiblast, continuous with that of the external 

 surface ; and (3) the proctodoeum, or anal section, 

 also lined ^^by epiblast folded inwards from the anus, 

 just as the epiblast of the stomodieum is folded in 

 from the mouth. The mesenteron of the cockroach 

 is very short, as in other Arthropoda, and includes 

 only the chylific stomach with its diverticula. The 

 whole region in front forms the stomodoeum, and is 

 lined by a chitinous layer continuous with the outer 

 integument ; the proctodeum includes the malpighian 

 tubules, and extends thence to the anus, being lined 

 throughout with a chitinous layer. Wilde (Wieg- 

 mann's Archiv, 1877) states that the moult of the 

 chitinous lining of the crop follows that of the outer 

 integument. 



The mouth of the cockroach is enclosed between 

 the labrum in front and the labium behind, while it 

 is bounded laterally by the mandibles and first pair 

 of maxillcE. The chitinous lining is thrown into 

 many folds, some of which are loose and obliterated 

 by distention, while others are permanent and filled 

 with solid tissues. The lingua is^such a permanent 

 fold, lying like a tongue upon the posterior wall of 

 the cavity and reaching as far as the external 

 opening. The thin chitinous surface of the lingua is 

 hairy, like other parts of the mouth, and stiffened by 

 special chitinous rods or bands. The salivary ducts 

 open by a common orifice on its hinder surface. 

 Above, the mouth leads into a narrow gullet or 

 oesophagus, with longitudinally folded walls, which 

 traverses the nervous ring, and then passes through 

 the occipital foramen to the neck and thorax. Here 

 it gradually dilates into the long and capacious crop, 

 whose large, rounded end occupies the fore-part 

 of the abdomen. When empty or half-empty, the 

 wall of the crop contracts, and is thrown into 

 longitudinal folds, which disappear on distention. 

 Numerous tracheal tubes ramify upon its outer surface, 

 and appear as tine white threads upon a greenish- 

 grey ground. 



Four layers can be distinguished in the wall of the 

 crop, viz., (i) the muscular, (2) the connective, (3) 

 the epithelial, and (4) the chitinous layer. The 

 external or muscular layer consists of a single series 

 of annular fibres, usually distant more than their own 

 width from each other, and enclosing a still looser 

 stratum of longitudinal fibres. Here and there the 

 bundles divide. In most animals the muscles of 

 organic life, subservient to nutrition and reproduc- 

 tion, are very largely composed of plain or unstriped 

 fibres. In Arthropoda (with the exception of the 

 anomalous Peripatus) this is not generally the case, 



