'S7i Zoological Collections. Invertebrata. 



that it is an organ which contributes to digestion -. it receives an infinite 

 number of blood-vessels. 



' A yellow^ duct occupies the v^^hole length of the upper part of the intes- 

 tinal canal. It was first observed by Redi. De Blainville takes it for 

 a mesenteric vein, and Sir E. Home for a canal which conducts the eggs and 

 the young worms into the lateral cellules, regarded by almost all authors 

 as respiratory organs. This duct, which M. Morren calls cftloragogene, 

 appears to him to belong to the digestive apparatus, and to be vicarious with 

 the liver. Among the appendages of the intestinal canal are remarked the 

 numerous diaphragms which unite it to the submuscular membrane. 



The old opinion, that the earthworms respire by their whole skin, is 

 still held by more than one naturalist. It was first professed when the 

 infinite number of small membraneous sacs of these animals was unknown ; 

 but since their discovery, most anatomists have considered these sacs to be 

 respiratory organs. Sir E. Home saw them for the first time in 1817, and 

 took them then for what M. Morren also believes them to be, respiratory 

 organs. Some time afterward, the former naturalist supposed them to be the 

 receptacles of the young, which could pass out from them, and leave their 

 chrysalidic cocoons at the outer orifice of the excretory canal ; cocoons, which 

 would thus form what less clear sighted authors have taken for feet ! 



Whatever M. Diiges may say, we owe to Willis the real discovery of the 

 heart in the Lumhricus ; but its structure was only well known after the 

 observations of Home and Carus. M. Morren has farther perfected our 

 knowledge on this subject, and has shewn that the heart is com|)osed of a 

 series of dilated and contracted rings, communicating with middle dilatations, 

 which he compares to the ventricles, whilst the former would be auricles. 

 Like M. De Blainville, he admits that the dorsal vessel is the principal 

 artery, or aorta, and that the ventral vessel is the vena cava. It is true that 

 M. Duges has published quite a contrary opinion ; but M. Morren does not 

 adopt the ideas of the Montpellier professor. M. Morren gives an ex- 

 tremely detailed description of all the vessels, which he luunbers at 1246. 

 The blood does not appear to contain globules, but an innumerable quantity 

 of bullae, an appearance which the author thinks is owing to extravasation. 



The generation of earthworms has been for a long time very obscure, 

 and, when first examined, the subject gave origin to the strangest opinions. 

 Here, however, as elsewhere, the first observations of the ancients are 

 nearest the truth. Montegre, and after him Cuvier, suppose that the 

 young pass out alive from the anus ; Lyormet, Dufour and Duges, that the 

 animal lays eggs ; and M. Morren, that both opinions may be true. He 

 has seen small living worms come out by the ai7us, as well as large eggs 

 laid, which have produced young Lumbrici. These ova, however, which he 

 calls capsules, are only true cocoons, analogous to those laid by leeches. 

 M. Morren calls those black masses, so well figured by Home, foetiferous 

 bodies ; and he also found in them calcareo — horny productions, and ova. He 

 calls the former, in imitation of Sir E. Home, chrysalidic cocoons ; but in 

 his preface he says, that they might be the first states of the ovum more 

 developed. The ova have, moreover, different characters before and after 

 fecundation. When the chrysalidic cocoons are opened in the interior of the 

 body, the young are born alive ; when they are expelled closed, their 

 development takes place in the earth, and they are then called oviparous 

 worms, although they are really not so. M. Morren states, that a young 

 Lvmhricus, born on the 28th of September, three millimetres in length, was, 

 on the 1st of April following, six centimetres. This observation was made 

 in a chamber in which the temperature was never lower than 8° of 

 Reaumur. 



The concluding part of M. Morren's work is dedicated to the narration 

 of experiments which the author made on the power which earthworms 

 possess of regenerating parts of their organs. This faculty has been much 



