xxii HISTORICAL INTRODUCTION 



Lizards and Birds. The old mistake that the heart has only one 

 auricle is repeated, but he states correctly, contra Swammerdam, 

 that there are not two carotid glands on each side, but only one. His 

 views on the skeleton are dominated by his adhesion to the vertebral 

 theory, which he accepted in its most extravagant form. The whole 

 work is useful as a restatement and discussion of previous literature. 

 A more important contribution by Carus to Salamandra research is 

 his paper of 1 8 1 9. In this he describes correctly the parts of the gut, 

 and gives details of the female genitalia. He found the ostium of the 

 oviduct, and wondered how the large eggs could pass through it. 

 Although the eggs develop in the uterus they are entirely free, and 

 there is nothing corresponding to a placenta. Neither is there any 

 connexion between the foetus and the egg membrane. The anterior 

 abdominal vein is interpreted as a persisting foetal structure, and 

 comparable with the umbilical vein of the Mammalian foetus. He 

 gives a good account of the gross anatomy of the larva, including 

 the gut, and believes that the yolk mass is contained within the gut 

 wall, and is thus nothing more than an inflated section of the gut. In 

 fact both the yolk-sac and the urinary bladder or allantois remain 

 within the body wall — unlike the condition found in Mammals. In 

 his last paper dealing with the Salamander (1828) Carus publishes 

 two original figures of the trunk and limb muscles of S. terrestris^ 

 but the only mention of these figures in the text is to be found in the 

 description of the plates. They illustrate the more superficial muscles 

 of the head, body-wall, limb-girdles, and limbs. 



The genius of Rathke was first exercised in an inaugural disserta- 

 tion on generation in Triton which was published in 18 18. Two 

 years later it was expanded and reissued, and now included the Sala- 

 mander as a closely related form, the two genera being systematically 

 compared. He describes the development of the fat-body and its 

 relation to the general metabolism of the animal. In starved indi- 

 viduals the fat-body dwindles and even disappears, and during the 

 winter it is used up. All the fat in the body of the Salamander is 

 concentrated in its fat-body.^ The development of the genitalia with 

 their ducts, as far as it can be followed with a lens, is attempted for 

 the first time. The growth of the eggs in the oviduct is given in 

 detail, but he regards them as efflorescences of the ends of the 

 ovarian vessels. His mistake that the eggs escaped through an aper- 

 ture in the ovary was corrected by Czermak in i 843. A comparison 

 of the finer structure of the ovary and testis led him to believe that 

 from first to last they are identical structures, the adult testis being 

 ' In these statements Rathke goes too far. 



